I'm using ATI's TV Wonder PCI [stereo, MPEG 2].
Unfortunately for me, I have to run it with very old drivers to get it to work correctly. Other people don't have any problems whatsoever. I paid $89 Canadian, so in USD, it should be pretty cheap.
I really don't trust ATI's drivers, but the TV image quality can't be beat for me.
You can also consider a All In Wonder PCI card from them too.