Pass and Seymour has CAT5 based multi-room audio system that can also try into a whole house low voltage network center (box). You can have all telephone, computer, intercom, security, television, and audio fed through the box. Fulton Electronics in Lansing/Jackson sells bundled low voltage wiring (2 CAT5 plus 2 RG6) for $0.39 per foot (half the price if bought separate and less hassle) in any quantity. (RG6 is HDTV ready.)
Much of this is going wireless. I'm also building a house and don't know what to do.