Using RTM ISO to install now, enter /upgrade/ key Oct.?

Hello there,

Can somebody hazard an educated guess or answer based on experience with Vista.

I pre-ordered the Professional upgrade. Currently running Vista business. Have RTM ISO. Wish to install now (maybe as clean install, maybe not) and use key come October.

Had I bought a retail full version key I wouldn't worry -- but having an upgrade key... how will Win7 react in Oct? I'll ask to activate, I will enter a key, and the key is an upgrade key...
If I had upgraded my Vista, will it remember? What if I had done a clean install? Will it just ask for my media?

With Win7's not-asking-for-key during setup, how does the upgrade key check thing work??

You can do fresh installs also with upgrade discs it just asks you to load the disc during install to confirm you have an older version of windows that is valid for the upgrade. I would assume you can do it also once it's fully installed. Just make sure you install the Professional version of Windows 7 now.

Edit: But from looking at this blog it seams unclear at this time.
http://blogs.technet.com/haroldwong/...ows-7-rtm.aspx

The requirements for using the Windows 7 Upgrade Media seems to not be fully documented and publicized. I received emails from folks who have said a Microsoft representative had told them that an activated copy of Windows must already be installed onto the computer. I had stated that the original media would be required. Since I cannot get a solid answer internally at this point, I’m going to take the egg on my face and say that I may be wrong in my previous statement. I am not sure yet. Since I don’t have access to the Upgrade Media myself, I cannot test it to know for sure so I am waiting for the Windows 7 Team to post an update to their blog that states all the requirements. Just like the rest of you, I will have to wait for further “official” news. I am very sorry for jumping the gun on this one and stating what I heard were the requirements for using the Upgrade Media.