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Backup all data dear to your heart to a usb stick or to a usb drive.
Next step is to make a 100% clean install.
After the clean install, you will only have a fresh copy of Win 7 on the drive.
here's the tutorial: http://www.sevenforums.com/tutorials/1649-clean-install-windows-7-a.html
You will notice that end of the tutorial are links to other tutorials. There is a tutorial for just about every imaginable situation.