Mythtv 0.20 is working great with Ubuntu Edgy 6.10 right now! Here is the trick, HD takes a lot of processing power!!! I tried with a couple of P4 2.4 boxes but I could not get things to tune and I could not get things to play. Here is a tutorial that I have been using to get this set up multiple times.
I finally stepped up and tried this whole set-up on a P4 3.2. Yes, it is faster than my current desktop but it works so well I don’t know if I even care. Shortly after setting up Mythtv (and getting the frontend to actually show up) I started scanning for channels. My Fusion card did a pretty good job scanning channels in QAM 256 and actually got 5-6 HD channels. Shortly after the scan I went back into the frontend to make sure I could watch the shows and they worked pretty well (not flawless but I defiantly was watching HD). The next hurdle to overcome is being able to record shows. Recording works without a problem but the station information (what shows are playing at what times, etc.) was not working. So now that is what I am trying to do. Get some information on channels (although channel 2 works fine).

Here are the steps I am taking to make a custom channels.conf file. Using the tutorial above install the nessessary tools

sudo apt-get install dvb-utils dvbstream
sudo apt-get install gxine mplayer

Then scan for some channels

sudo -s -H
mkdir /root/.tzap
scan /usr/share/doc/dvb-utils/examples/scan/atsc/us-Cable-Standard-center-QAM256 > /root/.tzap/channels.conf

Just to make sure I got all the channels I needed I repeated the last scan step with a few other options. You can find all the options for scanning by just doing

ls -a /usr/share/doc/dvb-utils/examples/scan/atsc

To be honest I have no idea if this is going to work. I am still scanning channels. I sure hope it does though. For now here are a couple other links that are helping me figure out this whole custom channels.conf file.

Until I finish all of these scans, wish me luck!