I have this card. It's pretty nice. It uses Samsung Tuners which are pretty good. With that in mind you need to understand the following.
1. OTA HDTV support is really crappy in canada right now as the "broadcasters" are dragging their heels. How ever if you happen to live in the toronto are of the vancouver area though you can pickup alot of DTV stations from the US.
2. As such Media Centre, and Media Portal don't work properly. media centre won't see the atsc tuner and media portal only sees it as the NTSC tuner.
How ever the reception is excellent where i am even with a crappy wire antenna. The media centre software that comes with it is ok for tv watching. Also Sage TV works beautifully with it.
If you have any other questions feel free to ask me as i own the card.