There are temp files, system restore and more. More than I can cover in 3 paragraphs. But if you visit the Vista forum you see at the top a sticky post and in there is the question "Where did all my disk space go?"
TREESIZE let's you find this space. And the 100 megs is quite normal.
Wait till you see what happens with the WINSXS folder!
I'm using windows vista home premium on a Toshiba satellite A205-S4777 laptop. I have a seagate hdd.
I've noticed that the amount of free space on my C drive varies on its own even when i haven't moved any data to or from it... (i perform a disk cleanup n clear all browser caches etc before i check the free space amt so i get a more accurate picture of the free space)
even when i've simply turned the computer on n left it alone for a while (no apps running as such) the amount of free space increases or decreases on its own when i check from time to time - the variation can be as much as around 100 megs
who's performing these writes/deletes on my disk? malware? (i have eset smart security installed n regularly updated)