Wow thanks for the input! I am always hesitant on this method because I dont have a lot of experience with working with drywall. Yes, we plan on painting the room... I just want a nice wall to paint! If I were only running cables to the left of the fireplace (which is where we will put our component shelf) how large of a chunk of drywall should I cut out?
I just cut about the size of a single gang back box wherever I need it. Something with a good angle in the direction I need to cut holes, then I cut the holes I need.
Pick up a couple of the home repair books to see how to properly patch the drywall easily. I personally just re-use the piece I cut out, put a piece of 1x3 wood behind it and screw it into the hole I removed, then spackle and sand several times.
The first few times is definitely scary, but then after you do it a few times you realize that if you put a bit of effort into it, the task really isn't that hard.
On the other hand, it also makes me realize I don't want to do an entire room of drywall because that would be some crazy sanding work to be done!