My secondary is the Garmin 478 at the helm (weatherproof small CP). But the netbook has a much better screen and the navigation software (Coastal Explorer) is far superior.

I interface it with the West Marine AIS 1000 (using a USB-serial converter) to show AIS info onscreeen and the AIS1000 provides GPS info on the same NMEA port/stream. Before I got the AIS I used a blue-tooth GPS tucked behind the windshield. I found I could also keep the Blue-tooth GPS inside the cabin (plugged into the 12v charging supply) and still get accurate position info.

If you're looking for free open-source navigation software check our Open CPN http://opencpn.org/