TV Wonder Elite
Whether you plan to build your own home theater PC or buy something preconfigured, the one area you don't want to skimp is the TV tuner card. You can easily find a good-enough solution for under $50, but the result looks like you routed the picture to VHS tape before sending it to the screen. If you want great looking video you need to spend a few extra bucks on the capture card. Until recently, a few extra bucks meant spending well into the hundreds, which certainly wasn't in my budget.
ATI recently released the TV Wonder Elite, which promises hardware MPEG-2 compression, 3D comb filtering and advanced noise reduction in a strategy to entice those of us who want great looking TV to upgrade our cards. By delivering hardware MPEG-2 compression, instead of the more typical software compression used to keep the cost down on cards, you get the advantage of playing back other videos or performing other computing tasks, without overloading your CPU (you still need as much memory as you can afford).
The TV Wonder Elite uses the ATI 550 Pro chipset, which is arguably the best PC solution for home theater graphics rendering. The card bundles a custom edition of CyberLink PowerCinema, which does program time shifting like Tivo (although I think the Tivo interface is still slightly better). The thing that makes this card a hands down winner in my book is ISF RL certification. Imaging Science Research Labs and Microsoft set a fairly high benchmark for artifact-free video playback and low noise imaging for video on Windows XP. To the best of my knowledge, this is the first consumer priced card to meet that specification. If you compare an image recorded with this card side-by-side with the live signal from the cable company, I almost guarantee the recorded image will look better every time.