Hi all, I would like to know if it is at all possible to perform a clean install of Windows 8.1 Pro RTM, using an upgrade (from win7) edition of Windows 8 pro install key? (legit) Is it as simple as just typing in the upgrade key in to the Win 8.1 setup, or do you have to install Win 8.1 with a different key, then activate it using the upgrade key??? Many thanks in advance. UPDATE... I was able to perform a clean install simply by typing in my legit Windows 8 Pro upgrade key when prompted during setup. After getting to the desktop, Windows reports that it is activated. So yes, you can perform a clean install of Windows 8.1 using a legit Windows 8 Upgrade Key.