Clean Install Windows 7 with Upgrade Media
 

It was the final unanswered question about Windows 7. But now, thanks to numerous reader reports and my own hands-on experience, I'm can now report that Microsoft is still making it difficult to clean install Windows 7 with Upgrade media. But fear not, there is some good news. While you can't simply use Upgrade media to do a clean install of Windows 7 on an unused PC with a blank hard drive, the workaround this time is easier than ever. Assuming you know the trick.

http://www.winsupersite.com/win7/cle...rade_media.asp