I was considering mounting the computer behind my passenger seat (pick-up with no x-cab so it'll be safe from people touching). I would run VGA and USB touch screen cables under the carpet. Most media files will be permanently on my computer so the pain-in-the-***-access to a DVD-ROM i can deal with.
Any thoughts on this? I think it also means easier mounting of future xbox and stuff. The only thing I'd have trouble with is running an extionsion serial cable to my hand-held GPS under on the dash under the windshield.
I use VGA and USB extensions both, had no troubles out of them.
Just make sure to tape the connections up really well so that they do not risk coming apart under your carpet.