What I use may sound kind of strange...a modded xbox console. All you need is Xbox Media Center ( free download ) running on a modded box and you can stream movies from your pc via windows shares. I've never ran across a movie it wouldn't play.
I softmodded mine so that i could stream movies to the bigscreen instead of watchin on pc monitor.
You can get a used xbox dirt cheap on ebay, just try to be careful so you don't get ripped off.
Im using a softmod, but i already had an xbox and i was curious. If i was buying now, i'd get one with a modchip and about a 200gig hard drive. Hardmod is much less headache.
I'm not sure about the 360. I'd just get a regular xbox ( haven't looked lately, but i'd imagine they are dirt cheap now ).
Yes it plays it all. Xbox media center uses Mplayer, which is a media player for linux. I watch a huge variety of videos, and I have never ran across anything it wouldn't play. Not to mention you can play games on the xbox too. Halo 1 is the greatest multiplayer game ever made IMO. = )
