thanks smufguy. bout to take a look at your post you suggested.I think I need to put my 2cents in.
We all come from different background with varying skills in computer building and methods of building. Some look for top of the line High tech stuff, while some (like me) look for something economical and work within a budget.
First place to start is here >>> http://www.mp3car.com/content/150-car-pc-101.html
I did 8 months of researching. Did not register to post and ask questions off the bat, but to read people's experiences, follow a hand few of builds from start and see what they did and 'how' they did it. Then incorporate my needs for an in car needs and functions at my finger tips. The reason for the install is to have a safe and less intuitive entertainment system that keeps my mind from wandering too much, hands on the steering and eyes on the road. I am not installing the system to play solitaire while driving.
This is my building http://www.mp3car.com/worklogs/14658...ter-build.html . First is to choose the parts that you need (choose, not buy yet), then choose the power-supply power requirement from one of the renounced power supply calculators and choose your DC-DC supply. Once the investment is made on hardware, there is no turning back (yeah you could return it and get another one, but its just a hassle) then pick your software and you are fine.
Do a bit more research and listen to the fellow members. These guys are great and know their stuff. Good luck with your build.