Free up to 20 GB of your Windows Vista Folder
Windows did it again, recently i found that my windows folder was 20gb size…
Blame it on System Restore and Shadow copies. Here is how to freed a lot of space (in my case more than 20 gb)
WARNING: Make sure there is no updates waiting to be installed and only use this solution after having updated all and restarted to make sure your system works good
1) Open the Disk Cleanup tool, choose cleanup for all users, choose your drive, then once it finishes analyzing the disk and the cleanup dialog pops up, click the “More Options” tab
2) Where it says “System Restore and Shadow Copies” click the Clean Up button, accept the warning and it will start cleaning. Once your system becomes responsive again, and you can hover over the buttons in the cleanup dialog, that means that its done
3) Open “Computer”, right click any empty space and click Properties
4) In the dialog that pops up, click on Advanced System Settings from the left nav menu
5) In the dialog that pops up after that, click on the “System Protection” tab
6) Wait for it to detect your disks (may take a bit)
7) Any disk that has a check next to it, uncheck. You will get a warning that you will lose all your restore points except the current one. Now click the Apply button and wait a bit. It might look like it’s done, but it usually takes a few minutes before you see any space being freed up. 
Once you get your free space and it’s done, you can check the checkboxes back to reenable system restore and shadow copies (just to be safe)
