I did a clean install when upgrading to vista and cannot understand why so much space is being taken up on my hard drive. I have two computers and it happened to both. I really don't want to install it again since I had to do it twice now. I've deleted the windows.old folder and have checked all the other folders that are visible to me to see what's causing it and nothing adds up. I've done a desk clean up and defragmented but still the same and I still haven't installed all my programs or folders yet which are on an external hard drive. Does anyone have an idea why and is there a way to ck exactly whats taking up space? Do updates take up a lot of space? Is it the registry that needs cleaning?... Thanks to anyone who has any advice!