The Nehemiah M10000 has a hardware mpeg2 decoder built in that should help with SOME dvd playback stuff. I have one of these boards and it was fine with most vid files and dvd's i chucked at it, plus you can run it fanless if you stick a Zalman blue NB Heatsink on the cpu
The cheapo (50 quid) mini itx intel atom D945GCLF board is all you need for sd xvid and divx etc.
Use the freeware media portal and you have an ultra cheap HTPC.
I tried it and had no problems streaming and playing xvids. I used an ide to CF adaptor and ran with xp and media portal on a 4gb cf. All xvids where streamed from a NAS.
It was quite a nice little system. The fans a little noisy, but I removed it an glued on a 80mm.
However I dumped the system as it wasnt up to playback of HD 1080p.
I had the via epia m1000 1ghz cpu for a small media center, and this played almost everything i threw at it, every now and then, a dvd would start to stutter, but i'm talking like 2 dvd's out of hundreds that were tried.
CPU usage would be around 90% most of the time when playing a dvd/divx file though.
If you want to run windows update on it though, do it over night, it takes aaaaaages!
Oh come on, thats a ridiculous comment. I am talking about in a home cinema environment.