Great idea, just a couple of questions:
1. What are you going to use to make the PSU compatable with the car's DC battery?
2. How are you going to connect the screen to the computer? A normal D sub video cable? Or does the video card have RGB outs?
3. Is it going to be hooked into your sound system at all? If so, will you be sticking with the stock system or upgrading the HU, amp, spearkers, etc?
Thanks, and good work! :D