When I got my new computer I went with XP Pro 64 bit. I really like it. Poser 7 flys, and I expect the new Poser Pro will do even better.

The only "complaint" I have with it is that there is still alot of programs that aren't compatable ( for example Adobe Flash isn't 64 bit compatible). So I am just having to be patient until the rest of the world catches up.