How do I get additional language files?

With additional language files, you can change the display language on your computer so that you can view wizards, dialog boxes, menus, Help topics, and other items in Windows in a different language.

There are two types of language files:

Windows Vista Multilingual User Interface Pack (MUI).‌ Windows Vista MUIs provide a translated version of most of the user interface. MUIs require a license to be used and are only available with Windows Vista Ultimate and Windows Vista Enterprise. If you are using Windows Vista Ultimate, you can download MUIs by using Windows Update. If you are using Windows Vista Enterprise, contact your system administrator for information about installing additional languages.

Windows Vista Language Interface Pack (LIP).‌ Windows Vista LIPs provide a translated version of the most widely used areas of the user interface. LIPs are freely available to download, and most LIPs can be installed and used on any edition of Windows Vista. Because not all of the user interface is translated, LIPs require at least one parent language. The parts of the user interface that are not translated into the LIP language are displayed in the parent language. When you download a LIP, you get the parent language requirements for that language. The parent language pack needs to be installed before the LIP can be installed. For more information, including a list of languages available for downloading, go to the Microsoft Local Language website.

Additional Info: http://windowshelp.microsoft.com