A language pack changes the language of the Windows Operating System. The default language is always English and other languages can be installed manually. All the language packs are described in KB2483139. Here is the list of language packs available from Microsoft for direct download:
Download Official 32-bit (x86) Windows 7 SP1 MUI Language Packs
Please note that Chinese (Taiwan) or zh-tw language packs are not available at this time. If someone finds the language packs, kindly let me know through comments. You may also be interested in how to use Vistalizator for Windows 7 sp1 to add a language pack to any edition of Windows 7.