Did you buy a copy of the upgrade but wanted to do a clean install on a fresh drive? Yeah, me too. So rather than having to install Vista or XP first, you can do a little bit of work to get it to accept your key.
The important thing to remember is don’t activate or enter your key! It won’t be accepted anyhow 😉 What you want to do is follow these instructions. It involves a quick edit to the registry followed by a quick entry into the command prompt.