OpenCPN and the free NOAA charts... openCPN is free and open source software adn works very well. It's not a resource hog, like so many programs these days so it will run on older machines. very intuitive interface...
no idea why anyone would spend money on software.
there is also SeaClearII, although i find the interface clumsy.
OpenCPN also works well with bahamian charts.
been using it for 2 years now, couple of round trips up and down the east coast, a trip to Houston and a number of runs to the bahamas... it's my primary planning tool as well as my main nav system underway with a Bluetooh receiver.