Using a GA license key to register the RTM

Perhaps nobody knows this yet but....

I was going to use a spare copy of Windows XP Pro on a new PC I've built and in conjunction with that plan I pre-order the Windows 7 Business Pro Upgrade when the discount program was available in late July. Instead of installing XP Pro a friend of mine had me install his copy of Windows 7 Business Pro RTM that he downloaded with his paid subscription to Technet. Instead of registering the RTM with the RTM license key our plan was to re-arm the RTM until after the GA release on October 22nd and then use the key from the upgrade I've pre-purchased. Since both versions were Windows 7 Business Pro we figured there would not be a problem. So.....

Does anyone know if I will be able to use the license key from my pre-ordered upgrade to Windows 7 Business Pro to activate the RTM copy already installed on my PC? Since I would have had to do a full install from the upgrade CD anyway and the purchase of the upgrade is completely legal since I based on my ownership of a Windows XP Pro license it seems logical that I should be able to use the key but somone on another forum suggested that this was not going to be allowed and that I would have to start over again. Does anyone have any info on this?

If the key you purchased is for the edition of Windows you currently have installed, you will be able to activate permanently with your GA key. I plan to do the same thing (re-arm until GA) with my install of 7 Pro.

Here's what seems to be the crux of the issue..... What everyone is telling me is that the RTM is a full version of Windows 7 Pro whereas what I purchased is an upgrade version of Windows 7 Pro. If it works like I had "assumed" then I could use the license key from the upgrade version of Windows 7 Pro I purchased to activate the copy of Windows 7 Pro that is on my PC. However, what several people have now told me is that you can't use the license key from the upgrade version to activate the full RTM version. If you have any insight on this one way or another I'm appreciate your feedback.

Note that one person that sent me a thread on another forum indicated that I as a worse case situation I could install the Windows 7 pro from the upgrade CD without a license and then go back and upgrade the upgrade (double install) and use the activation key on the second install. Not sure how that will work in a situation where I already have the RTM installed. Any thoughts on this would be appreciated also.

Sorry Moondoggy, I can't really say with any certainty because I have no experience yet with how 7 will handing retail upgrading. If it works like Vista did, then I believe you should be fine though...

Thanks to everyone that replied. I'm still feeling a bit dazed and confused over how the upgrade CD is supposed to work so if anyone would like to add to this thread feel free to provide your input. The question that is confusing me is whether your not you do a clean install from the Windows 7 Pro Upgrade CD?

The way it is supposed to work is that you have Windows XP or Vista installed and you launch setup from within the OS. Setup sees what version of Windows you have and acts accordingly either blowing away XP or allowing you to upgrade Vista. Since this is the way it's supposed to work I've been told by many that I must remove my Windows 7 RTM and install XP first before attempting the upgrade.

On the other hand MaximumPC and the new Windows 7 Secrets book both claim that you can boot staight from the CD and elect to install Windows 7 once without providing an authorization code and then installing it a second time with the authorization code.

Anyone want to weight in.......

From what I've read, you should be able to do a clean install, and it should ask you for the install disc of the previous Windows you are "upgrading" from just to validate you are eligible to upgrade.

If you already had Windows installed on the system and you start the installation from inside it (regardless of if you overwrite it or do an inplace upgrade) then it should be fine.

The only way to know for sure without being able to personally test it myself is to just give it a try though, sorry.

From what I've read in MaximumPC and in the Windows 7 Secrets book they know (or believe) that Microsoft will follow the model used in Windows Vista Upgrade that will not prompt you to insert an install disk to confirm eligibility on a clean install. Strange as it seems I guess that the Vista upgrade would allow you to install a copy as a clean install as long as you did not attempt to enter your activation key. After the install was complete then you ran setup again and this time you entered your activation key. So the reality was you were upgrading from the upgrade. Both of these sources indicate that Windows 7 upgrades will work the same as Vista Upgrades.