This article describes how to get Firefox to display Chinese, Japanese, and Korean characters on web pages.
- (Windows XP): See Install East Asian language files on your computer at Microsoft.com
- (Linux) Most distributions come with East Asian support. If it doesn't work, use your distribution's package manager to install the font packages for the languages you need.
Windows 7, Windows Vista, and Mac OS X come with East Asian support built in. For more information, see Multilingual support (East Asian) at Wikipedia.
Based on information from Installing East Asian language support under Windows (mozillaZine KB)