It is all the rage among the geeky crowd to build tiny PCs to put
under the seat of your car for GPS navigation, music, etc. You can
buy them off the shelf, designed to run on 12vdc. For example:

www.mini-box.com
www.mini-itx.com
www.logicsupply.com

Some of them even have composite video outputs. Or you could use a
cheap VGA-to-composite video converter. I have one that I use for
presentations at venues that have only video screens. Cost about
$50 and draws power from the USB port of my laptop. But you definitely
lose some resolution.

EarthLCD (www.earthlcd.com) sells a 7.8" LCD screen with VGA input,
but the resolution is only 640x480, and contrast is only 45:1.

A lot of the mini-itx form factor PC motherboards can drive an LCD
screen directly, but I have not had much luck finding bare color LCD
screens in the 5-7" range, nor details on how to hook them up to
a mini-itx motherboard.


Happy hacking,

Ross Oliver