I have a Windows 7 Media Center PC on the same LAN (192.168.x.102 and 192.168.x.107) both plugged into a 3548 XL. I know that the streaming wants multicast and UPnP, but the UPnP wouldn't be something I'd be checking on a switch. The router is an 881W, and I've enabled routing and multicast. I don't see anything on the 3548 XL specifically for multicast - is it on by default? Do I need to do anything with IGMP? The 881W does have firewall capability, but I'm pretty sure it's off by default. The firewall on the Windows 7 machine is off. Any suggestions?