Ed...
As to seeing the various sofware packages work, warrentees, etc... best suggestion would be to go to a boat show and spend the day going from one booth to the next to see whats what... I agree w/ Bryce and Bill... I have both "Nobeltec Visual Navigator" and "The Capt." running on a (cheap E-machine) desktop at the nav station on my 420. I have one (inexpensive 15") flat screen at the nav station and another that I can put up into the cockpit to see the chart display there. Actually I have 2 E-machine computers, so that if one fails I can simply swap it out with the second. All, at a cost much less than one marineized laptop. (Been running this setup for the past 2 1/2 years, with few problems). Nav. Station GPS delivers NMEA data to computer sofware. I don't interface with autopilot, because it would make me TOO complacent. I used to "poo-poo" computer nav. sofware.... ie... "real sailors don't need that stuff, bla., bla., ", but, after seeing it on friend's boats, and how wonderful it was, I saw it differently. Now, I wouldn't go out without it... you know EXACTLY where you are and where you are going. Real NOAA charts are displayed with your boat positioned and moving on the chart in its exact loaction. Routes, waypoints, ETAs, etc., etc. are all right there, instantly updating... You can go places, (through shallow areas, for example) with confidence, because you know exactly where you are. It's like steering your boat on a vidio game. I like "Vis. Navigator" better than "The Capt" because I like the presentation, etc., but that's just a personal preference. Anyway, good luck, and hope you find what you like.