System Preferences > Network > whatever connection type (Ethernet Connected) > Advance (button) > WINS (tab) > MSHOME (or whatever the name of the workgroup is)
the xp box showed up in the finder. i clicked on it and the shares showed up in the window.
cool.
on the xp box, i should have done the above first, but, anyway, on the xp box, i deleted all my network places. i then "set up a home or small office network." using the network setup wizard.
I am also having problems - Leopard can see my XP computer in the finder but DOES NOT see my Powerbook running Tiger at all. Why not? The finder preferences are set correctly.