I'm not much help with tuning digital cable. There are some fancy analog solutions that do high-def hardware encoding of the output from your tuner box. There are also QAM tuners. Maybe somebody else can contribute more on this. I just do ATSC tuning, and still end up with way more recorded TV than I have time to watch.
I can say I've had good luck with a wide range of TV tuners. I've had an ATI, Aver, and Hauppauge and all of them have been appliance quality.
Currently I'm using a Hauppauge 2250 because it's nice to have two ATSC tuners with only a single slot and cable coming into the computer.