Notice I said "Digital" TV.
Analogue signals are also carried over the cable line, and will continue to be carried over the line until January 1, 2009. At which point, the analogue signals will completely disappear, and hooking it up directly to your tuner will no longer work. You will have to:
a. hook up a cable box to the S-Video input on your PVR-150, much better video reception, there.
b. hook up an HDHomeRun to the cable, to recieve the digital channels. Of which, what I said above, applies.