<< in-dash retracting monitors that are
 capable of VGA input.  For this reason, I'm leaning towards the in-dash
 solution provided I can use the display with a PC. >>

For this I might consider using a small desktop motherboard and building it
myself. It would allow for expansion and keep the costs down.

As far as the monitor most PCs and Macs as well as all new laptops offer "S"
video out for use in a video capacity. therefore I would suspect that you
could buy a small Phillips retractable TV and wire it this way. this would
allow for DVD MP3 ETC and the integration of the GPS through the PC granted
that you have the proper software. I would put it all behind the dash or run
long USB cables to a box built into the rear of the Van ie under the seat or
whatever. There are portable folding keyboards and rollor mice that you could
use for interfacing. I would build this into the Westy table arm (probably
make my own platform that would allow it to swing around whilst in the
forward facing postion and not to ruin the original table for resale reasons).

Dunno, just a thought.

Chris