There are wide variety of interface languges in Ultimate and Enterprise versions of Windows Vista and Windows 7 and you can select any of them. Basically this is beneficial for those whose native language is not yet included in off-the -shelf copy of Windows. There are two type of language packs which are available for Windows Vista and Windows 7.
MUI and LIP
The MUI (Multilingual User Interface) packs are available only with Ultimate and Enterprise versions of Window Vista and Window 7. There are 34 MUI language packs available for both 32-bit and 64-bit versions of Window 7 and they can be downloaded through window update as optional extras.
The LIP (Language Interface Pack) consists of small installation files for less common languages and works on any edition of Windows. However there are certain requirements regarding original copy of your Windows (usually English). LIPs can only translate the more commonly used parts of the user interface. There are many LIPs available for more obscure languages from Armenian to Welsh.
Every User account can have their own language. In order to change the language for the user account you are currently logged in on, just open Control Panel and click the ‘Change Display Language’ link. For the classic start menu, it can be found in ‘Keyboards and Languages’ tab. When you double click on ‘Regional and Language’ icon, you can install and uninstall languages from here as well as select the interface language from the ones available. To change the inteface language you only need to log-off and then log-in again. There is no need to restart the computer.