Since someone else already revived this old thread, I'll just toss out this little nugget.
The original Xbox makes for an EXCELLENT little home theater PC. You will need to install either a modchip or a softmod of some kind, but if you're more or less done playing games with it, who cares? Once you get the mod installed, you put on a copy of XBMC. Finding the Xbox version is a little difficult, but if you do a search for "T3CH" you can find one.
The original Xbox has pretty much everything you need. It goes from off to ready to go in under 30 seconds, it has networking, surround sound capabilities, you have a multitude of options for connecting it to TVs, it uses relatively little power. There's an internal hard drive that you can use to store ripped copies of your DVD collection so you can preserve the discs. The only real drawbacks to the original Xbox is the hardware just isn't up to the task of 720p or 1080i decoding, but it can upmix almost any format to either of those resolutions. Microsoft should really consider removing the game playing capabilities from it, refresh the hardware to something a little more modern, and selling it as a HTPC. They would make a killing IMO.
The Xbox is really was quite the versatile little device. Pretty lackluster as a game console, but more than made up for by it's secondary possibilities by virtue of basically being a legacy free PC.