Good post on how easy it is to upgrade from the RC version of Windows 7 to RTM. Did this myself and it works quite well.
Note: If you are using a customized version of a Windows 7 it will probably fail.
Upgrade Windows 7 RC to RTM | FettesPS
Note: If you are using a customized version of a Windows 7 it will probably fail.
Upgrade Windows 7 RC to RTM | FettesPS