installing 2nd tuner card

[sub]

That's a little tough to answer. When I scan in WinTV, it only comes back with 21 QAM channels. However, when I scan with GBPVR, it comes back with considerably more. (Sorry, I didn't bother to get an exact count, but it seemed like at least 60 or maybe even more.)

This because GB-PVR list all the channels it finds, even the encrypted ones you ones that you wont be able to watch. I'm fairly sue WinTV only returns the subset that a Clear QAM (ie unencrypted).

I'm sure you'll only find a small subset of those channels found in GB-PVR's scan will work for you. The rest will be encrypted.