I have used quite a few different combinations of GPS/computer/DR w/charts and I prefer to use the charts and hand nav skills and then check them with the GPS. This keeps my nav skills sharp and also allows me to tinker with the latest technology. If you are going to hook up your hand-held GPS to a laptop, definitely get an external antenna. Check Ebay for one that fits your unit.
Be aware though, the refresh rate on the mapping software, the GPS unit and real life are not exactly in sync. Can be a bit dicey in a narrow, busy area like a river or harbor entrance as well as trying to keep in a channel. Rely on your eyes and instincts first and foremost, and check them with the technology. NOT the other way around.
I have seen sailing instructors rely on the technology and go aground!!!