If you are using an RC or Beta version of Windows 7 it should by now give you some problems. The RC will stop working on 1'st June but from 1'st Feb it will shut down in different intervals without saving the current work (making it unusable).
MS claims that there is no way to update the Beta or RC version to full product, but expiriance tells us otherwise.
To update the RC or Beta something has to be done the the installation files. 1
Copy all files from installation DVD to your hdd, go to sources directory and search for cversion.ini
it should look like this:
To allow update the MinClient should be changed to something lover then your current version 7000 should work (it worked for all RC's that I had)
Modify the file to something like this:
Then start the setup directly from the hdd. It should be able to update your Windows 7 RC to desired version.
Because most RC were English the only possible update will be to English (I mean Base language not MUI add on). If you had other RC language version then you will be able to only update to that language. This is one thing that can not be changed. But because Windows Ultimate has MUI it should not be a problem.
If you have other interface languages installed they will bee uninstantiated during the update, and will have to be installed after it.
I have read that there is a possibility to downgrade from Ultimate to other edition but I have not tested it.
Take note that it is possible, but not recommended to make such update. Some things might not work.
I have also noticed that sometimes during the update some application preferences are lost (reported missing Outlook contacts, Firefox bookmarks) so you should make an backup of all important data.
This method is not 100% tested there still will be some specific configurations that wont survive the update - but till now I had not one such case.