Does LLTD use any specific port to operate?

I have a wireless network in my house. My XP machine can see and access folders on my Win7 machine, but Win7 cannot see XP at all. I have LLTD installed on XP and I have opened inbound/outbound UDP ports 137,138,5355,3702 and TCP ports 139,445,5357,5358 through ZoneAlarm Pro on XP and Windows Firewall on Win7, but to no avail. I have the same workgroup name on both machines.