Alright I've been doing enough reading, it's time to start getting my project together, you guys have convinced me :) .
This is what I'm looking at for a system.
Lilliput 7" Touch Screen - Touch Screen
VIA EPIA MII10000 Mini-ITX Mobo w/ LVDS - Motherboard and Chipset
Casetronic Black ITX-2699R Mini-ITX Computer Case w/ PCI Riser Card, External PSU - Case
Kingston 512MB DDR266 Memory - Memory
CarNetix CNX-P1260 12V DC-DC regulator - POWER!
The hard drive I haven't decided on yet if I want to go internal or external since I like the thought of being able to bring my Hard Drive into my house etc.
Also I'll be adding WIFI and Bluetooth hopefully as long as I can find cheap enough which will connect to my Motorola V600 for GPRS access. I'll also have a bluetooth keyboard and mouse in the dash and wire a USB hub into my arm rest in the middle of my truck where there will also be an external firewire/usb DVD burner. In the hub will be a smart card reader for my digicam.
I'm concerned about the comptuer though since it is 2.5" tall (which I know is tiny!) but my trucks seats sit really low so I have to do some measurements but I'm praying it will fit. The LCD I'm also worried about, I may have to mount it outside of the dash which I'm afraid to do due to security reasons (I go to school in Worcester, city life is harsh, especially in Worcester).
I plan to watch Circuit City for any amp deals (free installs) so I don't have to deal with that then just wire everything up and cross my fingers.
Any thoughts, concerns, ideas would be greatly appreciated. Thanks again guys this site has worked wonders for me!