i am not sure where you are at with the development, but i thought this info might help
most, if not all, digital tuners support BDA drivers in windows.
http://www.microsoft.com/whdc/archive/broadcast.mspx
check out mediaportal or gbpvr, couple of media centre apps, and it may give you some ideas of how to best implement TV support. it would also be great if you integrated the EPG/XMLTV functionality at the same time. hell, why not include the pvr function too!
ok now i'm getting carried away but you get the picture