althou no veteran, would suggest this (logically)
From the choices you listed and if you have space in you car, I would suggest 2-5-8
If you don't have that much space and/or wanna mount the comp under the seat go 3-5-8
BUT if I were you, I would get a mini ATX mobo, custom case it and mount it under pas. seat. I personally find CarBox software the easiest to use, but many people like Media Engine, etc. So thats a matter of taste. For monitor search on ebay for Lilliput - cheapest.
Overall, just search for everything (lcd monitor, software, motherboards, touchscreen - whatever makes sense) and you should come up with lots of answers. Sometimes even too many,which makes it very hard to choose