I too like watching TV on my computer. For some time I was bouncing back between ATI All-in-winder, Nvidia personal cinema, and even the Matrox eTV solution. To be honest, none of these solutions satisfied me completely. After many many iterations I've settled on SEPARATING the TV functionality from the video card altogether. Believe me, I am MUCH MUCH happier now!
That is... for the last few years I've been running a plain old AGP graphics card + a brooktree based pci TV-tuner card (think Hauppauge WinTV PCI or Leadtek TV2000XP/EXPERT + agp video card of your choice). If you can spare the PCI slot I highly recommend you do the same.
I have found that this setup is far more reliable/compatible/portable (and ultimately usable) than any single board solution [I'm typing this on my FreeBSD/x86 computer as I watch the Mets play the Dodgers]. In addition, if you want to upgrade your video card to one of the latest and greatest chipsets (think GF7000 series) you don't need to shell out tons of cash for a board that has a tv-tuner as well, after all, the tv-tuning is being done by the PCI card (no need to upgrade that too).
It may be too late for some, but I'm hoping I can save some heartache for others.
That's my story... and I'm stickin' to it!