I would just do a clean install. The RC and the Betas were not meant to be used as production machines. I never did. I would test various pieces of software out for a couple of hours, or whenever I got new hardware or new software, I'd install them and test them under Windows 7. However, my main work was still being done in Vista until I my copy of Windows 7 came in the mail.
I would really suggest NOT doing the "upgrade". Do a clean install. I always do because you just never know what stale crap is still lying around. A clean install ensures all stale dlls and such are gone and you are starting from a clean slate.