I use Maptech's Offshore Navigator s/w. I connect my handheld GPS's Garmin 48, 72, GPSMAP 76, using a data cable, to a USB port of my laptop. Sometimes data cables have a serial plug and you have to use a serial to USB plug converter.
After you connect, following simple setup screen, your GPS reltime position will be plotted in the chart you are displaying in the laptop.
Maptech Chartkits include a CD with the corresponding paper charts.
You can also download charts from the maptech site.