The pros use a program called "D-Tools", at least we do where I work. Its quite expensive so I know its not what your looking for. All it basically does is allow you to make blueprints and wiring diagrams, along with a few other nifty things like making proposals etc..
Not sure what you want to do with the software, but you can always import drawings into CAD or Visio and draw a bunch of stuff in.
I saw your other post and im not sure how much experience you have with this sort of thing but I think that it might be a good idea to get a professional installer in on the project because theres alot of things you need to think about to really do this right.