The Japanese Language Tools system is available on several different platforms. What are the differences between them and which one is right for you? Here's a quick summary of each; for more information you can see the reviews and spec sheets I've linked to, and of course you can find more online.
First, general information: Despite the wide range in prices and ages, all of these PDAs have almost identical specifications and capabilities. There's been a lot of hype about new operating systems and "features," but in reality the technology hasn't changed significantly from the hx4700, the oldest of the three, to the brand new iPAQ 212. Performance (speed and stability) is pretty much the same across all three PDAs (still top of the line!). All of them are also compatible with all computers (slightly more compatible with Windows computers, but you can do just about anything you need or want to through a Mac or Linux computer, too), and all of them will also work perfectly without any computer at all.
The dictionary features and Japanese input systems are the same on all four PDAs, as described on the Complete System page; in addition, all three share the following specifications:
Hewlett-Packard iPAQ hx4700: Review, Spec Sheet.
The hx4700 has been refurbished by HP Japan to like-new condition, and indeed it looks and performs (and lasts) like brand new. Indeed, all of the parts subject to wear and tear (with one exception; see below) have been replaced with new parts, including most importantly the touchscreen, outer body, and battery. This allows me to sell a PDA with top-of-the-line features in same-as-new condition for much less than the system would cost with an equivalent new PDA. As for reliability, I've sold over 50 of these, many have been in customers' hands for over a year now, and not a single one has had a hardware problem.
Notes: This PDA runs on the Japanese version of the Windows Mobile 2003SE operating system. While the OS is in Japanese, remember that on a computer most of your interaction is with programs, not the OS. The EB Pocket Pro program used in the dictionary system has an entirely English interface. Most of the parts of the OS you do need to access are either labelled in English, in katakana transliterations of English (e.g., "File Explorer" is "ファイルエクスプローラ") or obvious icons. There are fewer than a dozen words with kanji you'll encounter in normal use, and you'll soon come to recognize them by context even if you don't bother to learn the actual kanji. In short, the Japanese OS is far less difficult to manage than most users expect. The body is largely made of magnesium (a strong, light metal). The battery life will carry an average user through 2 days of average use (total 5-6 hours, depending on use and settings). Downsides. The larger and brickier shape is less comfortable to hold or stuff in a pocket than the lithe Axim X51V, though it's smaller than the iPAQ 212. Because of the memory set-up, if battery runs down completely, the iPAQ will hard reset, losing all data in the main memory--fortunately, because of the excellent battery life and very smart systems, this will probably never happen to you, and even if it does you can restore everything from your last backup quickly and easily, even without a computer (this sounds like a big deal, but it really isn't). Because of the memory set-up, user should make sure to install large new programs and save large data files to the memory card to keep the main memory as free as possible (not hard to do)--and because of how the OS works, installing software to the memory card (as recommended) involves one more step than on the Axim or new iPAQ, though it's still quite simple.
Included Accessories (other than those mentioned above): 4 GB SD card; HP owner's manual on PDF; ;clip-on hard plastic screen shield; generic screen protector; 30 day money back guarantee; 1 year hardware warranty; 3 years support.
Dell Axim X51V: Review, Spec Sheet
This is the PDA I recommend for most users. The memory and OS are a step up from the hx4700, right on par with the new and far more expensive iPAQ 212. The X51V has been refurbished by Dell USA to working like-new condition, and indeed it performs, lasts, and largely looks like brand new. All of the working parts subject to wear and tear have been replaced with new parts, including most importantly the touchscreen, main battery, and internal backup battery. The body of the Axim is replaced if the it shows more than very minor wear. Everything else is thoroughly tested and replaced if it doesn't perform like new. This allows me to sell a PDA with top-of-the-line features in same-as-new condition for much less than the system would cost with an equivalent new PDA. As for the reliability of refurbished Axims, I've sold over 150 of these, many of them have been in customers hands' for over a year, and not a single one has had a hardware problem. Moreover, before I found the refurbished X51Vs, I sold over a hundred systems based on several-year-old used, unrefurbished Dell Axim X50Vs, with almost identical hardware to the X51V, and even those used units have had remarkably few problems. My favorite point about the X51V, compared to the two iPAQs? Ergonomics. It's a bit smaller, with rounded corners and edges. The result is that, even in a metal case (highly recommended), it's much more comfortable to hold and to slip into a pocket (the iPAQ hx4700 would be uncomfortable in a pocket, and perhaps even impossible when you put it in a case, as you really should; the iPaq 212, even naked, is too big for a pocket). Being able to carry it comfortably in my pocket means it's there when I need it--a PDA that isn't is no good to me at all. Battery life is more than sufficient for a full day of normal use (~3-4 hours total on-time on normal settings with dictionary lookups, study with a flashcard program, some time online via Wi-Fi, wasting some time on games, etc.; about 9-10 hours just listening to music with the screen off). Double-size batteries are available for the Axim, though I think it's more practical to simply carry a tiny, matchbook-sized spare if you really think you'll need more power.
My favorite non-dictionary use: the Axim is my GPS navi unit when hiking and driving. Unlike phone-based GPS navigation systems that are becoming popular, this one works wherever you go (the phone-based units pull their maps from the cellular network--which means that, outside the 3G signal areas, they simply don't work, and even in covered areas you spend a lot of time waiting for maps to load as you drive).
Big note: The Dell Axim X51V as it was originally released was a great piece of hardware crippled by the horrible Windows Mobile 5 operating system. JLT has upgraded the OS to WM6, and now the Axim really flies. It's as fast and stable as the two iPAQs. WM6 also allows the Axim to use SDHC cards in the SD card slot, increasing the memory capacity in that slot to 32 GB. Like all the others, it can also take up a 128 GB CF card, too, for a total capacity of 160 GB (and when larger CF cards are released, it'll be able to use those, too). WM6 also simplifies software installation and memory handling, and includes much better versions of the Microsoft Office applications (Word, Excel, PowerPoint, etc.) than WM2003SE on the iPAQ hx4700.
Besides upgrading the Axim to WM6, I've also customized the OS to offer full Japanese support, using the same systems used in the native Japanese version of WM. Japanese input and display look and work exactly like they do in the native-Japanese iPAQs. This means that they're part of the OS, so they're fully integrated and usable in every program and they work beautifully. So you get both the superb Japanese support you'd find in a native Japanese device and the ease of use of an English language operating system--the best of both worlds.
Included Accessories: 16 GB SDHC card; USB SDHC card reader; JLT documentation, Dell Owner's Manual, and backups on DVD; generic screen protector; soft slip case; stylus; power supply; deluxe sync/charge cable; 30 day money back guarantee; 1 year hardware warranty; 3 years support.
Dell Axim X50V: Review, Spec Sheet (links coming soon)
As supplies of like-new refurbished X50Vs have largely dried up, I'm no longer offering the X50V system. I'll leave this information up for reference, though.
The PDA itself is externally identical to the X51V, above, but has less memory (the same as the hx4700), and the memory is set up differently (also the same as the hx4700). This means that the user needs to pay some attention when installing new software and copying data (music, videos, maps, whatever) to the PDA to put them on the memory card. It's not hard, though (it's a bit easier with the English version). The Japanese and English versions have very different operating systems, so they're almost like different PDAs. The Japanese version has the same WM2003SE OS as the iPAQ hx4700, above, so all my comments about the hx4700's OS and memory set-up apply to it, as well. The English version has a custom WM6 OS, much like the one on the X51V, and most of the time in use it works pretty much the same way as the X51V. The OS even allows it to use up to 32 GB cards in the SDHC slot, just like the X51V. However, if used intensively, the English X50V can have occasional slowdowns in performance (if you're mostly using the dictionaries and basic built-in programs, though, you may never notice a slowdown--it's mostly power users who will be effected). To minimize these, it's important to keep the main memory as free as possible by keeping as many programs and as much data as possible on a memory card rather than in the main memory of the device. Again, people using just the dictionaries and the basic built-in programs (calendar, contacts, MS office apps, mp3 player) really won't be affected much, and even for power users, the slowdowns are a minor annoyance, not a crippling fault (it seems to be games that are most affected--most other programs use the processor and memory intermittently, allowing the Axim to catch up to itself while you're just looking at the screen and eliminating the need for big slowdowns).
Included Accessories (Japanese version): 4 GB SD card; extra-large 2250 mAH battery with custom battery cover; custom black aluminum case; JLT documentation, Dell Owner's Manual, and backups on DVD; generic screen protector; stylus; power supply; sync/charge cable; 30 day money back guarantee; 1 year hardware warranty; 3 years support.
Included Accessories (Japanese version): 16 GB SDHC card; extra-large 2250 mAH battery with custom battery cover; custom black aluminum case; JLT documentation, Dell Owner's Manual, and backups on DVD; generic screen protector; stylus; power supply; sync/charge cable; 30 day money back guarantee; 1 year hardware warranty; 3 years support.
Hewlett-Packard iPAQ 210 Series: Review, Spec Sheet.
(iPAQ 210/211/212/213/214--these are all the same PDA; the number varies by where and how you buy it)
(now available only a custom basis)
I don't recommend this PDA because it's not quite as good as the Axim X51V, but, because it's a new PDA and costs me much more, I'd have to charge much more for it. When it was a regular offering, I felt bad thief charging 70,000 yen for something that I don't think is as good as the system I charge 45,000 for, so whenever anyone asked about this I tried to talk them out of it.
It has the same features and performance as the Dell Axim X51V, but with a slightly larger screen (4" vs. 3.7") and about 2/3 longer battery life (though the Axim's battery is already more than sufficient). The body, though, is much larger than the Axim, even a bit larger than the iPAQ hx4700. The additional size means that there's no way this is going to ride in a pocket--you'll have to carry a bag for it or leave it at home. Also, as with most of the new WM6 devices I've tried, the touchscreen response isn't instant, as it is in the Axim and the older iPAQ--you have to hold the cursor down for a fraction of a second--a quick tap won't do. That seems to be by design, but I find it annoying. There's a similar delay when writing on the screen, too, which I find even more annoying--especially when I'm trying to write kanji. Someone who isn't used to the instant response of the Axim or older iPAQ might get used to it without ever noticing it as a problem, though.
The one advantage of the iPAQ 210 etc. is that it's new. I hear occasionally from people who are leery of buying a refurbished PDA and are willing to spend hundreds of dollars more for a new PDA that's no better. While a new PDA comes with a warranty from the manufacturer, the refurbished PDAs I sell have proven stunningly reliable--between that reliability and my service, not one of my over 200 customers would have been better off with a manufacturer's warranty. (In fact, if they get a new PDA, they'll have to deal with the manufacturer's 20 layers of "customer service," whereas someone who's bought one of my refurbished systems just has to send me an email to get a fast, simple response--and if it needs service, even after the JLT warranty is up I'll fix a refurbished system for just the cost of parts and return postage.)
I can understand why someone with different priorities might prefer the 210 (especially someone who won't be paying for it himself), but even then the best one can say is that the 210 has a minor advantage over the Axim in one or two areas. My own opinion is that the iPAQ 210 isn't as good as the Axim (or even the old iPAQ hx4700), so I don't want to sell the more expensive system without providing fair warning. That said, some people will strongly prefer getting a truly new system, even though the refurbished ones look, perform, and last like brand new, too. Thus, I offered the iPAQ 212 system.
Due to lack of interest among customers and my own lack of enthusiasm for selling a ¥70,000 system that's no better than the ¥45,000 system, I've stopped offering the system on a 210 series PDA as a regular offering. If you're really set on this model, you'll have to buy it and set it up yourself (setting up my dictionary system on the Japanese model of the iPAQ takes only a few minutes; if you get an English model, you may be able to add Japanese support to it--you can find advice online [sorry, I don't have time to help people set up their own PDAs]). If you want a 210 series PDA and really, really want me to buy and set it all up for you, I can do that on a custom basis. I can also, on a custom basis, set up the dictionary system on your iPAQ 210 series PDA if you send it to me (that'd be much cheaper for you than having me buy it). Please inquire on the order/inquiry form.