[Mac Medic]

Surge, so you have sharing enabled but cannot see any other PC's music library. I'm guessing file sharing on your network works and all PC's see each other in Network Places. iTunes uses Zero Conf to broadcast the availability of services, it would seem that they are either not broadcasting or no receiving. If you have Windows XP, chect to see if the built in firewall is blocking it. I guess you could have ports blocked on your router, but that shouldnt effect internal traffic. I would double check all my network settings, maybe assign static LAN IP's to each and go from there.