If you are using a firewall other than Windows Firewall, you must configure the firewall to allow incoming network discovery and file and printer sharing traffic. (1) For network discovery of other computers running Windows Vista, you must allow the following incoming Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) traffic: * UDP 3702 * TCP 5357 * TCP 5358 (2) For network discovery of computers running Windows XP and for file and printer sharing for both Windows Vista and Windows XP, you must allow the following incoming traffic: * UDP 137 netbios-name * UDP 138 netbios-dgm * TCP 139 netbios-ssn * TCP 445 tcp sharing (3) For network discovery of network devices, you must allow the following incoming traffic: * UDP 1900 (the ssdp port) * TCP 2869 For more information about how to configure your third-party firewall to allow incoming traffic, see the documentation for your third-party firewall. Notice: (2) is the only mention of Print / File Sharing. These ports will enable P/FS across many OS systems. Network discovery is no a prerequisite for P/FS Vista firewalls have the special configuration option to make the port Private vs Public and you need Private to access the shares on your LAN. Public is used to protect you at a Hotspot.