my favorit thing about the 360 is having all my divx movies and tv shows stored on my 500gb hd on the PC and playing them from the xbox.
i use the program TVersity, it shows on my network and streams flawlessly to my 360. i have problems wiht running media center on it, and this way is much much faster better quality as well and media center wont play divx files. with TVersity, whatver codecs you have on your PC it will stream to your 360. just browse to the folders, you have set up on your TVersity, click and play.
if anyone hasnt tried this, you need to!