WinXP PC not communicating with PS3 over wireless router

[Y3K]

OK here's the setup - My Acer (2006) windows xp home notebook and my newly bought secondhand ps3 (40gb). they are both connected to our belkin dfn7230-4 wireless router. my bud's mac, also connected wirelessly, will talk to the ps3 and stream files to it no problem - but my windows xp pc will not broadcast the media server. intel 845g pro wireless adapter.
network is configured with WPA2 protection.
UPNP is enabled on the router, and ps3 test shows UPNP as available. PS3 connects to PS network and browses internet fine.

ssid service, upnp, windows media networking services all are on automatic, and started.
are there any tools that can tell me if upnp is working on my computer? or can tell me if there might be a firewall blocking the data? i have tried disabling windows build-in firewall, but this has no effect. have tried putting the ps3 in dmz, then the pc in dmz instead. no go.

i am open to any suggestions. please ask for any more information needed.
Thanks in advance.