I think Using the laptop is great. I have done that as well, and was very pleased by the screen size and ease of viewing. The only downfall is the fact that they donnot like the least bit of moisture, wich can be a problem in any boat, even a hard top boat just from sweat. So keep that in mind.

I used a Garmin hand held Map76 that i connected to the lap top, wich basicaly just used the antenna of the unit, and i ran the Garmin GPS software that worked great.