You definitely dont have to hack up your car to do the computer part. The screen can get tricky, but a flip out style screen with vga input and touch could be the answer. You could easily install the pc in the trunk, under the seats (some say this is a no no) or in the glove box. None of these things are prefabbed for the most part, which means you make it what you want it to be! From what i understand, a single din pc will lack power. If you want it to do anything else besides play music, than you might consider going larger. Look around in the Fabrication forums for some ideas, or the worklogs area.