Microsoft shipped their Windows OS with multi-language support available only in Windows Vista Ultimate or Enterprise, or Windows 7 Ultimate or Enterprise. That means, for other Windows Vista / 7 versions, like Windows Vista Home Basic or Windows 7 Professional, users are not able to change their OS interface.
Now, with Vistalization (http://www.froggie.sk/), lower end versions of Windows Vista / 7 can change their Windows user interface just like the native multi-language support from Microsoft.
Vistalization supports Windows Vista and 7, from Starter to Professional (Business) versions. A wide range of languages are supported, including Chinese, Japanese, Korean...
Languages supported (as listed on the developer's website):
•Bulgarian language ***
•Chinese (simplified) language
•Chinese (traditional) language
•Croatian language ***
•Estonian language ***
•Latvian language ***
•Lithuanian language ***
•Portuguese (Brazil) language
•Portuguese (Portugal) language
•Romanian language ***
•Serbian (latin) language ***
•Slovak language ***
•Slovenian language ***
•Thai language ***
•Ukrainian language ***
*** partial support
I've been successfully changed one Chinese Traditional Windows Vista Home Basic computer to English version. Another English Windows Vista Business also successfully converted to Traditional Chinese user interface. Results to my satisfaction.
Next, what I'm going to do is to change a Windows 7 Home Premium laptop to Korean user interface, which I believe will be with very promising result.