Clean install Windows 7 from Upgrade media

As many of you might know you cannot activate a Windows 7 clean install done with upgrade media, this mainly has to do with a registry key that blocks it.  Here is a quick and easy way to activate.

Open regedit, navigate to this key:
HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/

Modify DWORD value "MediaBootInstall" from "1" to "0".
Close regedit.

Open a CMD prompt with administrator rights (right click command prompt, run as admin).
type: slmgr /rearm

Reboot, run activation wizard and complete activation, all done!