Microsoft recently upgraded the Xbox 360 with a neat feature; Divx playback. That means the console can now play back most downloaded AVIs. All it takes is a little media server sending the files to it over the network. If you believe Microsoft, your only server option is Windows Media Player 11.
Except that WMP 11 is totally evil. Because if you turn on file sharing, somehow wmpnetwk.exe ends up consuming 100% of your CPU. Even when you're not sharing files, and even when you aren't downloading a new video. All the time. Judging by the Google search I'm not alone in having this problem. And what a pernicious bug; 90% of Microsoft's users will never understand why their computers are suddenly terribly slow.
Fortunately there's a bunch of third party alternatives for servers. The only one I've used is the demo of TwonkyMedia, but it seemed to work well on Linux.