So I followed this thread and got my Air2PC o.2 card working. Thanks guys.

Now I put it into an existing setup of R5C7 with a PVR-350 (not using the output)

When I go to 'watch tv', it brings up 'tuner 0' (the 350) and regular tv stations work, but I get 'gray fuzz' on the DTV stations. I get to the DTV0 tuner by a roundabout route:
From the 'normal' channels, I open Pix-in-Pix, and it brings up a DTV picture on the other tuner. I then swap the P-i-P to the main window & I'm in business.. operating on the Air2PC I can run thru all the channels.
I doubt that this is an intended procedure however, did I miss something in setup of the two tuners ?