I thought so! That's why MS provided some answers already to quesions like that one. Windows 7 Help & How-to
"Can you upgrade from the 32bit Windows to the 64bit?"=querstion You won't like the....
MS answer= Can I upgrade from a 32-bit version of Windows to a 64-bit version of Windows?
No. If you are currently running a 32-bit version of Windows, you can only perform an upgrade to another 32-bit version of Windows. Similarly, if you are running a 64-bit version of Windows, you can only perform an upgrade to another 64-bit version of Windows.
If you want to move from a 32-bit version of Windows to a 64-bit version of Windows, you'll need to back up your files and then perform a custom installation of the 64-bit version of Windows. For more information, see Installing and reinstalling Windows*
For the second question = "Can I upgrade from the RC to the final version of Windows 7?"
MS answer = "When you install the final version of Windows 7, you'll need to do a clean installation. So plan on backing up your data then reinstalling your applications and restoring your data." http://www.microsoft.com/windows/windows-7/faq.aspx