Touchscreen monitor for a car?

I was planning on buying a GPS for my car, but decided instead to build a little computer with a GPS unit and a touchscreen monitor.

I've noticed that monitors designed for car media players are significantly less expensive. Such as this one:

http://www.amazon.com/Power-Acousti...-Screen/dp/tech-data/B000P51O3W/ref=de_a_smtd

Specs on another page says it was two 'AV inputs'. So if I use a composit connection it seems the video from the computer should work. My concern is the 'touch' ability. There must be some sort of loopback to the computer for the touchscreen to register what you touch... right?

Any ideas about this?

 

I have read about this before.he used undervolted Athlon 64 and kept the CPU and stuff under the seat.

 

I have an Athlon 64 X2 6400+ just sitting around unused with everything I need except a motherboard and monitor, I might use that. If I do I will definitely need to under volt as my power inverter isn't very good.

However this whole plan seems bad if I will need to spend $280 on a 7" touchscreen monitor. That's why I'm hoping I can use one designed for an entertainment system .

On second thought, I'll use a standalone touchpad velcroed to my armrest & a standard non-touchscreen lcd monitor attached to the ceiling. Maybe the following if all is compatible:

http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=2410504

http://www.amazon.com/Roof-Mount-Co..._7?ie=UTF8&s=automotive&qid=1213906007&sr=1-7

 

Just go to Mcdonalds and steal the one on the counter