If the problem is the UAC, you will have to uninstall the game, disable the UAC, reboot and then reinstall the game.
I never had any problem with two different computers both using windows vista (and now 7) x64 bits
Others have commented to install in a different folder like
C:\Ageod In my case never needed to do it, by default the games go to
C:\Program Files (x86) because they are 32 bits applications. They run fine, the saved games are where they are supposed to be...
IMHO the first thing tom do after getting a vista/7 PC is to disable the UAC and left it this way
