Though your question is a tad confusing, it's certainly not unanswerable.. The short answer is no you can't "Upgrade" in the sense of the word.. That is, the RTM IS the GA.. The code is identical because both are the same thing.. It's not like going from the RC to the RTM.. In that case, your dealing with two different sets of code..
In summation, you can't Upgrade from the RTM to the GA.. You can purchase the Upgrade media and use the "Clean Install with Upgrade Media" trick but a direct Upgrade isn't recommended or desirable in the least in my opinion..
I hope this has answered your question, if not, I apologize if I misunderstood what you were asking..
Microsoft doesn't allow consumers to install Windows 7 by downloading and creating an ISO. It decided to stick with old fashioned physical delivery. A Technet membership would be worth it if the software could be used in a production environment. Which makes it useless to people who need to run an OS on their computers every day.
Drew - does a Technet or MSDN EULA that says software downloaded from Microsoft can only be used for testing evaluation or development apply only to beta software? I was under the impression the EULA says one may not install software downloaded from Microsoft for use in a production environment. That is the only limitation that sets it apart from OEM/retail Microsoft products. An RTM may not beta but I would bet one would need to get a retail license to make it legal to run it in a production environment.
And the EULA does not make clear the difference between evaluation/testing and development and a production environment. Its all very vague.
I hate to say it but the EULA is somewhat contradictory to itself.. And I agree completely NormanF, it IS very vague when you actually sit down and read through the entire thing.. But in the end it's doing it's job, which in my opinion is to educate but not without confusing in the process...