Unfortunately it most likely isn't a simple driver
issue; the fact is, Windows 7 and XP don't play nicely when it comes to network anything. Here is what I would do:
1. On the XP machine, open the network connection properties. You should see items like IPv4, etc in this window. Do you see something called Link Layer Topology Discovery? If not, you must download it.
2. On your Windows 7 machine, go to your Network folder. Does a gold bar come down from the top saying "Network discovery is not enabled"? If so, click that bar and enable it. Do the same if it says anything about file and printer sharing.
Go with that for now; let us know if any of this works.
Sent from my Evo 4G. Please to excuse my engrish typing