Disclaimer: The following is no official advice or anything. I just did it and it worked ON MY MACHINE. Fell free to try but have a backup of your data.
The Windows 7 RTM bits will not allow an upgrade from an earlier version of Windows 7 (e.g. RC or beta). I belief that Microsoft did this to ensure that your new operating system works just fine and no beta and release bits get mixed up.
For the upgrade from the beta version to the release candidate quickly some patch occurred which allowed an upgrade. I used the same one and it works fine on my machine to upgrade Windows 7 RC to RTM.
What’s to do?
You need to change one file on the installation DVD. On way to do this is to copy all files to your computer, change the file and burn a new DVD. Since the upgrade will be run from within the already installed Windows 7 you do not need to boot from this DVD. I just copied all files to a USB drive and run the setup.exe from that drive. I belief you will be able to install Windows also from a directory on you local hard disk containing all the files from the DVD.
source folder you will find a text file named
cversion.ini. The original file looks like:
[HostBuild] MinClient=7233.0 MinServer=7100.0
Just change the
MinClient number to the build version of you current Windows version. For the Windows 7 RC it will be
The upgrade should work fine now. But if your new Windows 7 starts acting strange don’t blame Microsoft or me. Always remember you installed it with an unsupported patch.