you could give Vuze a look, it's mostly a torrenting program but it does also have a really good section for streaming media over your wifi network from pc > 360 the main issue with it is you need to start up your PC and the program before you can get access to all your content on the 360 every time, just kinda sucks for me because my PC is up 2 flights of stairs where my xbox is inside my ground floor sitting room.... if I wanted to go 4 flights of stairs before using a console I'd start up Kinect hah :D
Oh Vuze is pretty smart too if you have a bit of a dodgy streaming ability with your router has a converter for media so it would definitely work in SD on the Xbox where ever it is, but it is capable of streaming HD files too, just very much down to your own hardware.
Why not check me out on youtube and help me on the way to 2k subs over at www.youtube.com/stormcloudlive
