The newer computers from Apple have an extensive capacity for multilingual computing. You can change the default language of your computer (regardless of where you purchased it). Even if your default is English, you can still input and read Japanese (as well as many others). More amazingly still, you can create multiple user profiles on your Mac with different language settings for the menus, and then you can change between them with a single mouse click.
http://www apple com/support/manuals/ (added 2006-02-03)
A good (if a bit old) overview of different platforms. Part of the University of Washingon's Techical Japanese Program site.
http://www tjp washington edu/computing/japanese/guidetojapanesecomputing html (added 2002-05-05)
Microsoft Global Input Method Editors (IMEs) allow computer users to enter complex characters and symbols, such as Japanese characters, using a standard keyboard. Free download for Windows systems. Global IME for Office XP works in any Office XP product, while Global IME 5.02 works only in Word 2000, Internet Explorer and Outlook. Caveat: E-mail and web sites you create may not be readable on systems that don't use these products. Recommended mainly for those whose needs are limited to Internet browsing, e-mail and document creation for printing in Japanese.
http://www microsoft com/windows/ie/downloads/recommended/ime/default asp (added 2002-02-19)
Discusses the pros and cons of the Global IME solution for using Japanese on an English verison of Windows, then moves on to discuss partitions (allowing you to add a operating system). Also discusses Windows 2000's improved support for bilingual computing.
http://home nyc rr com/computertaijutsu/dualos html (added 2002-05-20)