Windows 7 - Upgrading to different "version" of Windows 7

Seen a lot of traffic lately about folks wanting to be able to upgrade their Windows RC (or later) install when the final comes out, with most of the discussion about what will be saved.

I have a different question (but I suspect I already know the answer) ...

The prereleased versions have been Ultimate 32-bit and 64-bit. In the past, I believe it was NOT possible to "downgrade" from Ultimate to something "lower" (e.g., Business, Home Premium).

So, unless everyone running the prerelease version is planning on buying Ultimate (and I'm guessing most are NOT), then I'm also guessing it won't be possible to install a release version (e.h. Professional) over an existing RC Ultimate installation. Right?

If this is true, it makes most of the "can I upgrade to the release version?" questions moot.

I think majority of the people here are going to reinstall a clean copy of the RTM build once it is announce. Some people may already have the supposed RTM build, and will just keep on using it until their software ships/becomes available, then they will input their key and activate Windows 7.

You do make a valid point though, that you cannot downgrade a system from Ultimate. This is something people need to keep in mind too. If they are installing the supposed RTM build and selecting "Ultimate" as the version, when their copy arrives and it is a Home Edition, they will have to rebuild.

I think the majority of the people here are conformable rebuilding their machine and will happily do so when the final products ships/becomes available.

I see you mention upgrading an RC to an RTM, which is something I cannot recommend. I am sure someone has the process documented, but I would suggested starting out with a nice clean slate on a nice new operating system. When it is officially release, I suggest installing it from scratch.

Hope this answers some of your questions.

Thanks for the replies. While I agree that upgrading from RC to RTM is not a good idea, I was more interested in knowing if it was even possible. I have existing Vista installations on several PCs, all "higher" than Home Premium -- but in looking at the features advertised in Seven, it no longer makes sense for me to run anything other than Professional.

I really posted this more as a question to see if anyone knew of any "tricks" that could be done to overwrite an Ultimate (or other) version with a "lower" version and have it still work.

Since I do regular full-image backups, I can try that later and simply see what happens, but I'll most probably do clean installs.