Lots of software out there. I assume you're on a Windows platform.
I've used Ocean Navigator successfully for several years, and like it very much. Maptech has several levels of compatible programs.
ON is great for planning and underway navigation. It has a nice feature which allows you to plot a course, with waypoints, and to print out a copy of all the courses, distances, times, waypoints, etc. I always do that before a long trip, and have the hard copy along as well as the program itself running on my laptop.
Here's an example of a course w/waypoints plotted on a NOAA chart of the Fox Islands Thoroughfare in Maine: http://gallery.wdsg.com/Maine-Trip-2004/FoxIsTh?full=1
I also keep an older Dell laptop runniing Win98SE and ON, with the identical routes and waypoints and charts. It's cheap insurance in case the IBM Win2K machine fails.
Others have their favorites, of course.