Upgrade type: In-place Upgrade/Custom (varies)
According to Microsoft, over 15 million people installed and activated the Beta and Release Candidate (RC) versions of Windows 7, 8 million of whom formally participated in Microsoft's pre-release programs, and 7 million who received the code otherwise. Even the 8 million figure--which Microsoft trotted out at the Windows 7 launch--makes Windows 7 the most heavily beta-tested software product of all time, and by far. And many of those people, using pre-release versions of the OS for several months now, will want to upgrade to the final version. Even if only one in 15 are interested in doing so, that's a potential audience of one million people.
There are a number of basic upgrade scenarios here, which unfortunately complicates matters. Regardless of how you intend to get from the RC version of Windows 7 to the final version, please note that these instructions, as always, assume that the PC you're using originally came with a valid, activated version of Windows XP or Vista. If it did, you qualify for any Upgrade version of Windows 7 and can install that OS to that PC however you wish. Don't let anyone tell you otherwise.
Here are some of the ways in which you may want to "upgrade" from the Windows 7 RC to a final, shipping version of Windows 7 using Upgrade media.
Note: The RC media was Ultimate edition only, so that's the only version (of the RC) we'll be referencing here. Also, be sure to thoroughly backup before attempting any of these upgrades.
Note: Microsoft does not support upgrading from a pre-release version of Windows 7 to the final version, so you undertake this task at your own risk. As always, be sure to backup everything before peforming any kind of upgrade or migration.
Scenario: You would like to perform an in-place upgrade from the Windows 7 RC (which, again, is Ultimate edition) to the final shipping version of Windows 7 Ultimate, using Upgrade media. (Note: I do not recommend doing this. However, I am documenting the steps for completion's sake. You'll get much better results with a clean install/migration.)
Type of upgrade: In-place
How to do it: Because Windows 7 is hard-coded to prevent in-place upgrades from pre-release versions of the OS, you can't simply upgrade directly with the Setup DVD for the shipping version of Windows 7.
Windows 7 Setup won't let you upgrade over the Release Candidate by default.
Instead, you must copy of the contents of the DVD to the PC containing Windows 7 RC (in a location like C:\install) and then edit the \sources\cversion.ini file in a text editor like Notepad. (Right-click it and choose Edit.) Change the MinClient build number to a value of 7100 or lower. Then, save the file and exit Notepad. Re-run Setup, this time from C:\install.
During Setup, choose "Upgrade," not "Custom." Then, assuming you have enough disk space to perform the upgrade--13 to 16 GB is ideal--you should be good to go.
Will it activate? Curiously, this has activated for me without any issues. If it does not activate for some reason, you can use activation method #2 from Clean Install Windows 7 with Upgrade Media.
Scenario: You would like to perform an in-place upgrade from the Windows 7 RC (Ultimate edition) to the final shipping version of Windows 7 Home Premium or Professional, using Upgrade media.
Type of upgrade: Migration (Custom)
How to do it: The process is basically identical to any migration, so you can follow along in Upgrade from 32-bit Windows Vista/XP to 64-bit Windows 7. Here are the steps: Backup all your data and settings with Windows Easy Transfer, boot the PC with your Windows 7 Setup media, and then do a clean install. Then, activate Windows and reapply your data and settings with Windows Easy Transfer, and reinstall your applications.
Will it activate? I'm still testing this scenario, but it has activated for me. If it doesn't work for you, simply employ activation method #2 from Clean Install Windows 7 with Upgrade Media.
Scenario: For whatever you reason, you tested the 32-bit version of Windows 7 RC, but would now like to install a 64-bit version of the final version of any Windows 7 product edition. (Or vice versa.)
Type of upgrade: Migration (Custom)
How to do it: I describe this process in Upgrade from 32-bit Windows Vista/XP to 64-bit Windows 7. Basically, you need to backup all your data and settings with Windows Easy Transfer, boot the VM with your Windows 7 Setup media, and do a clean install. Then, activate Windows and reapply your data and settings with Windows Easy Transfer, and reinstall your applications.
Will it activate? I have not yet tested this scenario, but based on the success of the other two, I'm guessing it will. If it doesn't work for you, simply employ activation method #2 from Clean Install Windows 7 with Upgrade Media.