After an upgrade to 7 from Vista? Wow, thats lame. If you could though, you might want to do a clean install. That guarantee you a trouble free install, usually. What I do for games is I have them on another partition/hard drive...though I need to reinstall all of them because I just wiped that drive recently.
None of the GOG games have installed correctly on 7 for me. I mean, the games work, but they don't work in GE.