Anyone experienced with Media PCs?

[Freakin]

Hmm, I'm having some problems with HD playback. I'm trying to play some H.264 1080p files and getting nonstop stutter. From looking around it appears as though there isn't any way to use hardware to decode the video, so it's putting it all off on my processor instead of the 8600GT with built in 264 decoding =/ I really don't want to switch to windows cause I've been enjoying playing with MythTV for the last 2 days.

Anyone know anything about how I could resolve this (outside of upgrading my processor)?