Right now, I've only got the dual LNB, but I have the oval dish that will let me attach a third LNB and I'll be in business.

If my DirecTV dish is grounded, then it's grounded somewhere in the attic rather than anywhere outside the house. Since I was planning to install the OTA antenna right behind and above the dish, I figure it's pretty easy for me to do all the grounding at once. I can run one grounding wire from the dish to the antenna, through the grounding block for the OTA antenna, and down the side of the house to a grounding rod of some kind. The electricity comes into the house on the same side, so I suppose I could do a grounding strap that hangs onto the big metal pole that comes out above the electrical box.

Where would you go to find the heavy-duty grounding wire and all the miscellaneous grounding parts? Home Depot? Should I call around to look for an electrical supply firm of some kind? I don't recall seeing the necessary gear at Fry's.