oh and another note, i've heard there's a lot of hoops to go through to run an XNA game in windows. i'd look into it before making a commitment.
Yeah, there's a good amount of people that have issues with running XNA games. Every contest at TIGS there's a few XNA games and they always get complaints from people who can't run them, or at least can't run them reliably.
I heard that Microsoft is working on the issue though so who knows, it might not be an issue much longer.