would the internal system be a extra selling point for selling the house in the future should the need arise...............drill sgt.

Yes, a built in central vacuum should increase the value of the house when you go to sell it. No vacuum noise in the house if the canister is mounted in the garage. Only have to carry a hose and attachment around, and the dusty air exits elsewhere instead of being stirred up in the house. Is the resale as much as the cost of the system and installation itself, who knows.