If you don't want the headache and want it done very professionally, talk to Tom at Villages AV. (I think that is his name. It's been awhile) I had him hang 3 TV's for me with the largest being a 75" on a concrete block wall. He did such a great job. He'll install the electrical, make sure all the cables are hidden in the wall. He even provides cables and the appropriate mounts if you need them, and his prices are reasonable.
Home Audio Video Sales & Installation in The Villages, Florida (352) 388-1677
There is no way I would use best buy over Tom. I've referred many people to Villages AV and all of them were very happy.
info@villagesav.com