I think that is fine. I don't think spending the extra cash to get the T7250 would make much of a difference on your processor.
The choice between Vista and XP Pro is a tough one. It is really a personal choice. One has to balance the fact that it is moving toward Vista and XP Pro's being tried and true and much simpler, in my opinion. Are you going with all 1710s? Because you would want the same OS on all computers. Just works better when you network.
Another thought, Microsoft is release Windows 7 soon if not already. It is Vista only improved. I don't think I would install Vista with Windows 7 coming out.
