Uninstall any useless programs from add or remove programs in control panel. Also use the disk cleanup utility, start menu / all programs / accessories / system tools / disk cleanup. Then use the defrag utility.
Also you can download either glary utilities or advanced windows care free from download.com.
Both are windows optimizing utilities that will make the computer faster and free up alot of disk space.
Also, delete all the restore points, that's if you have any. They will free up tons of space. You can get instructions on how to do tha, here: How to delete system restore points
A system restore point is made when any changes are made to the computer, automatically, wihtout your confirmation. e.g. Installed a new program.
Edited by genius12, 30 July 2009 - 04:20 PM.