Well, I just bought two ATI HDTV Wonders on eBay, so I guess it's gone beyond plotting.
I've read as much as I can without taking the plunge. In theory it should be fairly simple.
1. Acquire PC to use as a back-end server. This server contains the capture cards and the hard drives to store the recordings. Since I'm dealing with ATSC the CPU specs don't matter.
2. Acquire compatible capture card(s). Sure, there may be cheaper cards out there which you might be able to get working, but it's reasonable to assume if no-one has done it, it can't be done.
3. Download and burn the install ISO. I'm going to play with LinHES as it seems to be minimalist (so probably better for my needs). However Mythbuntu seems to have a more active community (and is on the current release of MythTV.
4. Install & test. In theory LinHES is also a LiveCD which will allow any computer to be used as a front end. If so, that would allow me to use another computer during the test.
5. Get PS3 interface working.
hda1 is the /boot partition, ext2 formatted
hda2 is the / partition, Reiser3 formatted
hda3 is the swap partition
hda5 is the /usr partition, Reiser3 formatted
hda6 is the /var, ReiserFS formatted
hdb1 is the /mythtv partition, JFS formatted