Make sure your 360 is turned on, then enable the sharing feature in WMP 11. IIRC, that's how I got it to work when I upgraded to WMP 11.
I don't know of any guides (off the top of my head) for that...look in the pinned topics in the 360 Multimedia forum and the 360 Software forum. Might be one there.
QUOTE(328iGuy @ Nov 8 2006, 08:44 AM)

What exactly are you trying to do between the two systems?
As far as I know the Pc needs to be running Windows Media Center, are you?
Nah, it doesnt'. Just needs XP with SP2 and either WMP 11 or Windows Media Connect to stream music, pics, and WMV.