Did you have to ask your daughter's nerdy—and honestly, kinda creepy—friend to come over and set up your TiVo? Then you've no doubt had trouble getting your Xbox 360 to play media other than standard DVDs. Good news for you, as Tweaktown's got a huge guide on setting up a PC and a 360 to stream DivX and XviD files on the fly.
The walkthrough goes into mind numbing detail on what PC to use, what codecs you need, how to set up port forwarding (not always necessary), and setting up the TVersity software. Old hat if you're a PC buff, but useful for everyone else.