Gary,
Given that I have a spare laptop but not a touch screen monitor that would involve some new $'s.... However, if I was gonna do that (and believe me I've thought about it when the wife wasn't monitoring the brainwaves!), I'd be tempted to go with a Mac mini for the 'puter - the small ruggedized, $500 package would be hard to beat as GPS/DVD player/MP3 storage device (with the obvious issues about reduced choices in GPS software). The mini combined with an LCD flat planel could be had for <$1k. Combined with bluetooth and a wireless card, you could use a bluetooth mouse and in some marina's log into the net. Just another thought but sort-of hijacking DoD's thread....