I currently use a ATi All-in-wonder X1900 with Windows XP MCE. It works pretty good, can record shows, pause live tv, etc. The things I don't like about it is that the tuner only does analog cable, not digital. So I still need to have the cable box, and the pos box comcast has doesn't even have s-video output. I also don't like having the video capture tied to the video card, if I decide I want to upgrade one of them, I have to upgrade both.
Ultimately I would love to have a PCI card that can tune HD Digital cable without the need for a seperate box, but nothing currently available can do it.