Ubuntu 8.04, The Hardy Heron
The neat thing is, you install Hardy inside Windows, and thereafter the Windows Boot Manager gives you the opportunity to load either Vista or Ubuntu. (The Startup defaults to Vista after a few seconds.)
Then, and this is the real psychic zephyr (it doesn't actually blow my mind, because Windows can do this too), Hardy finds and recognizes all the standard Dell hardware so your system comes up looking cool instead of like a refuge from Windows 3.0. That is, your touchpad works, your HID mouse works, your printer works, your screen works (at its intended size and resolution), etc. Feisty Fawn couldn't do that, or maybe it could, but you had to play around with third-party drivers. The Heron is Hardy, after all.
But... It's still boring. And tedious. Not everything is user-ready, let alone user-friendly. Japanese input method (although the fonts are there) isn't even installed by default, e.g. You have to learn to use a package manager, which, despite hiding behind a friendly-seeming "Add/Remove Software" menu item is still a ... fershlugginer ... package manager! Bottom line, get friendly with the real, full-featured, Synaptic Package Manager as soon as you're ready to move beyond Open Office (documents, spreadsheets and presentations), Firefox (browser) and Evolution (email).
There was a time when Microsoft had more or less the same reputation for cheesy sass and aging sophistication, with the singularly aggravating factors of high cost and even higher maintenance. But these days, almost silently, Microsoft seems to have mended her fishnet stockings and developed a little quiet class. Vista SP1 is very nice. I wouldn't run Hardy Heron on top of anything else.
If it weren't sorta fun, actually, I wouldn't run Hardy Heron at all. But it is, and I do. The Japanese puzzle is solved by System -> Administration -> Language Support, and checking the Input Method box. Japanese IME is called "Anthy" for some reason, and it's part of SCIM. After that, use the Synaptic Package Manager (it's similar to RedHat's RPM) to install Gjiten. This installs Jim Breen's edict, Kanjidic and compdic files (!). There is also a separate utility called KanjiPad which is not sufficiently mature, evidently, to be included in standard Ubuntu; Synaptic can install it, but frankly, you can't draw well enough with a mouse to successfully conjure up the character you're looking for — you'll need something like a Wacom graphics tablet, and frankly it's not worth it. Microsoft's IME has almost clairvoyant kanji-drawing, by comparison.
SCIM is straightforward. Ctrl-Shift toggles English/Japanese input. Romaji input works just like IME in Vista or Macintosh.