I've got a PC with vista, Norton 360 and Media Centre on it. It connects to t'internet via a wired BT voyager router. Xbox wired up to same.
Look at my network settings on PC and it sees the xbox360, media player is set to share with xbox 360.
Have disabled Norton firewll (although, it is automatically meant to cope with extenders)
media centre can't find the extender. Try coming at it from the Xbox and it fails on PC selected.
Am I missing something?