Alternatively, if you want to set another keyboard as Japanese so that you can use it in any program, follow these steps. (I'll show you in Vista, but it's basically the same.)

1. Make sure that you've installed the East Asian language fonts. If you do not have the files on your computer you may need your XP CD. If you don't have an XP CD you are either SOL or need to find it on a torrent. (There are torrents with the files).

2. Control Panel

3.

4.

5. (This menu should display the option to install East Asian language files. Maybe not this particular tab, but under one of them.)

6.

Then you should have a tab either in your taskbar or floating on your desktop that allows you to switch between keyboards. Make sure you choose your input style! (Hiragana, Katakana, Alphanumeric)