Can you receive hdtv signals on dig. cable?

Only if your cable system is transmitting HD signals. Only a few are, and I'm not sure what hardware you need. But the digital cable product most of us can get IS NOT HD, and requires a digital converter box even if you have a DTV. Picture quality not any better than analog on the ATT system in my area.

Yes; but you would have to buy a second round dish and point it at the HD "bird". The oval dishes are only 149 at C City and less on line, The OTA antenna-- along with a STB is the way to go. ( If you live in a large enough city) In LA here, all stations are in HD. Once you have a roof top antenna and the receiver(stb) the OTA programing is free. Cable will be doing HD soon, I've heard.

Thanks guys. Two more ?'s. What is STB? And while i'm at it, what the hell does YMMV mean?