It wont tune HD from the cable box, if that is what you are looking for. The card will only tune either over the air channels via antenna, or the equivalent channels from the cable straight from the wall.
With the local cable I do receive some HD programming without the box thou the number is limited. So, I'd need a quam tuner to receive on the card.. A card with a digital tuner won't receive the HD signal from the box. Is that what is being said? Is there a card that is just a pass thru? This is my first HTPC. Can you tell?