Andy Nifong has a nice post on his experiences implementing GP 10 on 64bit Windows. In the end, his solution sounds a lot like a the way to deal with GP on Vista, install it outside of the Program Files folder.
I recently did a test install on a box with Windows Server 2008 RTM and I installed it outside of the Program Files folder to help avoid UAC issues. Of course, it’s my box so I just turned UAC off for my testing needs but it seems that this process may solve other issues as well.