Saw this post earlier and did some research at Nibbles and Bits and MS Support. Even asked a + Member friend of mine on the Zone and so far, they haven't heard anything about this problem. But try these few things as I believe I found a few "hints" that might suggest where the problem lays.
Have your friend make sure he has the latest Video drivers for his card to start. Then make sure he has and is using DirectX 9.0a, the final realease not the beta. Available at MS. See what happens then. If still bad, he can try a different set of drivers for his video card.
Make sure he at least has the XP Service Pack 1 installed. This one fixed many problems for Zone gamers.
Tweaking Xp might help, as it sure could use some work. It robs lots of resources that could better be used towards the game.
I put a tutorial up at my site and even some little programs that help out XP and other Operating Systems run more efficiently.
http://www.brennt.com/hoppers
Systemax Sabre Ultimate gaming rig.
I got all the goodies and all the power I need to run anything thrown at me for the next two months!