hello
open windows explorer
goto tools/folder options/view

select show hidden files and folders
uncheck hide protected operating system files

you should find your missing space


now get this program to see whats using all that space


http://kanadepro.com/trial/acstrial.mv?ss8294

more info here
http://kanadepro.com/showsize/


btw
i tried this method and seen a differance in disk space size


cheers
egghead