Im starting with a basic P4 2Ghz pc with onboard everything (Video, sound) this is going to be powered by a standard Power supply from a 12V to 240V inverter. Have purchased a remote control on/off switch, that i will have hanging from my keys.
The head deck i will be receiving soon will have audio and video inputs and usb to control a 7" touch screen, it has a built in amplifier which i was going to run the speakers with (for now).
At the moment im just organising the placement of it in the boot where it will keep coolish and not visible, might have to underclock it for heat reasons.
If you have any more questions, ask away