Thanks everyone, actually I am putting a 1/2 rack into the bed under my Leer Cap. Into this I am putting in a UPS that is 12 volt to 12 volt regulated supply that will supply the PC with roughly 24 hours of battery run time if needed.
Below this I am mounting 4 1U Linux based servers using shock proof (we will see) Hard Drives. If worst case come salong I can always run solid state memory drives up 50 gig they have now but. the price is HUGE.
Below the PC/Servers I will mount a KVM up to a flatpanel touch screen mounted to the right of the GMC's cluster (above the radio). I figure the touch screen is more viable then a mouse in a truck.
Plan's are to run Verizon Wireless Internet to 1 unit w/ a Proxy Server/Log In Server. Then one unit will handle MP3's, one will push video (movies) and the 3rd will be used for the GPS/Mapping and Video Broadcasting.
I've done the laptop bit for some time, it just can't handle everything I have in mind for the truck.