The most often-asked question I get is, "What TV tuner should I select for my MCE PC?" (ok, by those in the US at least).  Tech Report compares the ATI TV Wonder Elite, eVGA NVTV (based on Nvidia's tuner design), and Hauppauge PVR-150MCE.  This is an article definitely worth reading.  I think the video quality comparisons are a bit too subjective, but it's a good comparision of any number of performance and quality gates in the technical sense.