41fb3f57__Packs_in_Win_XP_and_Win_Vista__1
[0] . [2] Some part of Win XP code is language dependent (e.g. country specific device drivers) [3] Separates the language resources for the user interface completely from the binary code of the operating system. All installations of Windows Vista contain at least one language pack and the language neutral binaries that make up the operating system. [1] 
MUI architecture
Creative Tester: Uncovering Myths about Globalization testing- MUI Packs in Win XP and Win Vista
1