I'm setting up my Myth box to use my new Infocus 61" 61MD10 HDTV, and having a much smoother time than I expected. I was going to get a PCHDTV3000 card to record HDTV, but later learned that it can only record over-the-air (OTA) broadcasts, not encrypted HDTV that comes over the cable lines.
Considering that our HDTV formats are still in flux, and might go towards cablecard in the next year, I'm going to just be happy with big, fuzzy regular TV recordings on a big screen. I think I'm okay with that. I decided that if I could get X working in full 720p resolution, that I could at least play HDTV recordings that I happen to find elsewhere.
So, I put in my NVidia video card with DVI output. I have a DVI->HDMI cable which I used to plug my Myth box into the tv. I was very surprised that my original xorg.conf file that the Ubuntu install created worked the first try with the DVI output!
TV playback is working great, but my HDTV playback with mplayer is stretching the videos width-wise, so I gotta look into why that's happening.
In any case, I found some good (?) Modelines here
I'll post my end xorg.conf in the next post.