Sounds like you want an ATI HD3450/HD3470. Any recent ATI/nVidia graphics card with DVI and a multifunction S-Video port will do just fine. I use an HD3650 on mine, got it for $80 so that it will have a bit of extra power over the next few years.
I agree, that's what I have done and bought a 3470 and I am happy with that purchase. I am not using it on a TV yet, I am simply using it on an old LCD monitor.