Dave the only bad thing, is being able to do that stuff yourself, a lot of builders will not allow you to run the wiring in YOUR house (even if it is low voltage), as its being built, that part would have to be in the contract before closing of the house. I have ran into this before, at first i couldn't believe it....
Don, if she hasn't closed on the house yet, make sure she asks the question, and maybe you and her, or others can help before the drywall goes up. Run the cat 5/6e, runs Everywhere you can think of. I cant agree with Dave more on this point. If you run speaker cable, you need to make sure you get speaker wire, that will be up to code in your area.
