I have a Raymarine 65 as my plotter and also run Maptech using Maptech cartography on my PC, an old IBM Thinkpad with Windows98, conected to a handheld GPS. I have always like the idea of having two different sources of information and having a backup system. I like alot of the C-Map cartography but the software to run it on a PC is prohibitive. I am considering buying a Standard Horizon CP500 which uses C-Map ( I have C-Map chips from my previous plotter) and Fugawi for my PC and use the Navionics card from my Ray. I have found a source of 12 volt computers on which I can customize the ports so that I can get serial ports as well as USB.
In order to run both a plotter and a PC at the same time you need to have 2 chips.