Although both the XBOX 360 and Playstation 3 can support UPnP media
streaming from Windows Vista, none of the video formats they use are
natively supported by the OS. Streaming is difficult without the use of
registry hacks, and it is undesireable to use transcoding programs like
TVersity.

Since Windows 7 adds native support for these programs, we tested the
streaming capabilities with both consoles. Will you be able to stream MP4
and MOV files straight "out of the box"? Read on to find out!

http://www.hardcoreware.net/windows-7-streams-media-to-xbox-360-and-ps3-seamlessly/

Thanks!