Ok so what I would do in your case is do a completely clean install of W7 and use a newly burnt cd
Sean webster has a download of W7 that is legal and free
it is legal to download W7 and microsoft has it available, however it is not free to obtain a illegitimate key and use that to crack it. Just saying for clarification
(midway down on that page is the DL link)
Before you do the install go into your bios and set it to AHCI and then format the harddrive you want to install W7 onto. This will insure that you have a completely clean slate to work with.
-side note- you can set it to ide but that is an older version and your mobo should boot just fine with either installed and AHCI is the newer version of stuff and imo works better
Then once your install is done then you should be able to copy all your files back onto the drive and you're good to go.
I know this seems like a long process but once you've done it a few times it take very little time to finish everything.