I don't want to scare you, but you might need to look into the issue of XP connectivity.
I have read (a while ago) about XP limiting connections to 10.
I am not sure what that will translate into - only 10 machines can connect, or only 10 concurrent?
All I can say is TEST, TEST, TEST.
Good luck and let us know how it goes.
"Still trying to shoot down that Red Baron"