Ok I will take a stab at this. WMP 11 is a media server that will serve media, movies, pictures and music.
WMP 11 will serve content to any media extender
You have to enable media sharing within windows media player.
This is for windows XP. Vista Home Premium has media center.
YOU DO NOT HAVE TO HAVE A MEDIA CENTER PC FOR THIS TO WORK JUST WMP 11.
No software is required for this to work with WMP11.
BTW I have a HP Media smart connect and I serve movies wireless using the 802.11N
Then just add content to your libary and fire up your xbox360.
I'm a PC and I play Poker