Last weekend we had the great pleasure of welcoming young BenT aka BentSailor on board the Womboat. May I say that he is a thoroughly personable young chap who brings along beer and lively conversation. He's welcome to come back anytime.
Flattery is always a good way to start a post.
I guess the big question for me would be what can't Linux do ? For example I know I can run Firefox and presumably Thunderbird on Linux but how about listening to music and watching movies ? Is it possible to run CMAP on Linux ?
Some of this we talked about on the weekend, but Ubuntu is probably your best brand of Linux here. It's very easy to install, probably has the easiest "How To..." documentation on the web, and one of the most open communities (i.e. you don't get slapped down asking basic questions - always a nice thing when starting out). It's also pretty much a basic office machine out of the wrapper - email, internet, word processing, spreadsheets, etc.
For videos and music, it comes with software for that but if it doesn't suit your tastes there are plenty of others. If there is something computer nerds get working on their machines quickly - it's ways to waste time listening to bad music and watching South Park videos
I am pretty sure (though open to being wrong on the issue) that C-MAP is Windows only. I've used OpenCPN briefly and it seems pretty solid. With that said, find someone who has used it on the actual water rather than playing with it in the office before relying on it too much.
The issue with Linux is that, while capable out of the box of most the basics, if you are interested in a specific application or task not done by every man & their grandmother - you can be disappointed by the inability to find the equivalent for Linux.
CrossOver Office is pretty damned awesome for running Windows software on Linux though. Unlike Linux itself, and most the standard software packages you can find for it, CrossOver Office is proprietary and you need to pay for it. That said, a good majority of the Windows apps I've tried on it have worked fine.