Jerry,

Like David P. I have and love my Standard Horizon CP180. Makes one lazy.

BUT, for short tips and planning I am LOVING LOVING OpenCPN a FREE! Nav program that has been working GREAT for me. You can also download a full world, YES ALL THE CHARTS FOR THE COMPLETE EARTH for FREE off of a foreign site. And from all the looking I have done that are very detailed!
OpenCPN is at: http://opencpn.org/download or just Google it up.
The charts are at: http://cnf.by.ru/cm93_charts.html (or close to this). From what I understand the download is a few hour affair. You need to download ALL of the files first, then you can unzip them.

I have used them with my small Eee PC (7 inch screen and only 8 Gig of hard drive) with OpenCPN, and a $25.00 GPS puck from Ebay.

Greg