Re: good cheap media servers
Mac Mini with a few external hard drives will work wonders. Front Row has complete Video TS (uncompressed DVD rips) support and you can catalog your DVD's much like iTunes via Front Row. The only downside is that the Mac Mini will have to be wired directly to your system for it can't stream video TS files wirelessly...yet. Hands down the cheapest and easiest way to go when it comes to a media computer.
Go PC and you'll be at the mercy of Vista and all that it implies.
Get yourself a Mini with Front Row. Download Mac the Ripper, and download DVD assist and boom you're stylin.' If you want to add wireless capability have an AppleTV sync with your Mini, but your video and audio will be compromised, however, if you won't be using the remote systems for critical viewing/listening you might be okay.