Basically about a month ago I modded my XBOX with a 120gig drive so I could use it to be a media center. I put about 60gigs of movies/tv shows on it (about 1/3 of what I have) and hooked it up to my HDTV in 720p mode and have been using it to watch 16x9 HDTV rips of shows and so forth I missed (first/second seasons of Deadwood, 3rd season of Alias, a ton of movies, Scrubs, etc).
Then about 3 days ago I decided since I had worked a bunch of overtime at work to pick up a 360 premium system and wireless adapter locally (so easy to get now). Picked it up... then realized 'crap I'm out of HD ports'. Right now I have my HD-DVR going into DVI, my DVD player going to my HD1 component port, and my 360 going to my HD2 port. That leaves my SD component, and multiple Composite ports.
So I was kinda upset that I had modded my XBOX so I could save time cause I used to have to use VSO ConvertXtoDVD to convert a few shows at one time to DVD and then the rest, but the process takes about as long as the shows so I have to hop up between episodes and burn/convert/burn/convert/etc. So basically I now have a modded xbox with 120gig HDD sitting around doing nothing cause it was a pain switching 360/xbox/360/xbox depending if I wanted to watch a movie, or if I wanted to play a game/live/etc.
Then... I found it. runtime360.com. Basically if you have a 360 + media center 2005 you can run this program in the background and it fakes the 360 Media Extender into transcoding the xvid files so they can be read by your 360 on the fly w/ no modification to your XBOX 360 needed.
So basically now I can stream all those video's from my main PC into my 360 in realtime using this app and on the fly. Which is awsome cause I have a whole bunch of shows to catch up on while I'm out of work for some family stuff.
If you ahve a 360 + a media center enabled PC check them out
(the actual XVid transcoder)
(the extender files for your PC to get it to sync w/ your xbox360)