41fb3f57__Packs_in_Win_XP_and_Win_Vista__1
[0] . [2] MUI Packs can be installed over English version of OS only. [3] Language Packs can be installed on any language version of Windows Vista. E.g. a user having Spanish Vista Ultimate can install German Language packs and switch between these 2 languages on the same system. [1] 
Mode of Installation
Creative Tester: Uncovering Myths about Globalization testing- MUI Packs in Win XP and Win Vista
1