If you put in the windows 7 install disk it should allow you to do a clean install (choose custom option, delete all the partitions) just by booting from the windows 7 disk. this WILL DELETE all your files and documents and programs though, so back up and your files and documents and make sure you have CDs/DVDs/ISOs of your programs so you can reinstall them. There is NO WAY to save your programs, they have to be reinstalled. Your documents can be burned to a CD though.