KevinD7288 said:
Use revo uninstaller
+1; Also, you won't need the .msi files that get left around from various installs. (search for *.msi)

My C:\Windows folder is 3.87 Gb compressed (6.01 G expanded) w/Win7 Ultimate; I deleted everything labelled japanese or chinese; some fonts; movie, sound and picture files and some other stuff: it wasn't easy.