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.

Sd- My experience was the same as yours and I changed over to DSS with basic analog cable for local channels. However, its not a very user friendly set-up. Lots of remotes, and complicated by the fact that most universals do not control all the functions on my Loewe TV and I've not mastered the art of programming my Pronto, which does. I did get an oval dish when I had the DSS installed, which I would strongly recommend. I also recommend paying for a real installer, not the hacks that do the "free professional install with one year agreement". They will mount the dish to the closest, lowest spot they can find, even if its the railing on your front porch. Very attractive.