FaiKee, on 26 October 2012 - 12:16, said:
The "upgrade key" is actually a retail key, so:
Unofficially: the key can be used with MSDN ISO's, MS wouldn't clarify on this, but it has been reported and confirmed by many users,
Officially: A PCBeta guy has asked MS China Customer Service, the key can be transfered to other machine(s), you can check with MS at your location.

How about the £14.99 key? From what I hear that's more limited and can only be used (non transferrably) on a single PC?
soulburner, on 26 October 2012 - 14:40, said:
I have a PC that has Windows 8 Release Preview installed. The computer has never experienced any other, earlier version of Windows. Are you guys 100% sure I can buy the $39.99 upgrade and have a fully activated, legal licensed RTM copy of Windows 8 Pro?
Thanks for clarification regarding the option to install on a clean drive, but it seems kind of too beautiful to be true to upgrade a release candidate to pro

Do you have a valid XP, Vista, or 7 license for *any* of your computers? Because from what I gather the license doesn't have to be limited to the computer the qualifying upgrade was brought for, as long as you have one computer with a qualifying license you can choose to install your upgrade on another.