You could start here:
http://www.eit.se/chartplotter/.
Java based
chartplotter software that should run under linux. I'm not a big Mandrake fan so I can't help you there. I know Redhat/Fedora pretty well and have worked on Debian lately. Personally, I'd just go Vista. If you're going to buy a new PC it's worth it. If you've got a decent laptop (that Armada has to be old, they haven't made the Armada
line in a long time if I remember correctly) why bother upgrading?
Here's another page of stuff for linux:
http://www.ibiblio.org/fplan/Aviatio...n-HOWTO-8.html
It says it's for aviation but I'm sure that doesn't matter too much.
The other thing you could do is run SeaClear under WINE. Check this out:
http://www.sping.com/seaclear/
Of course, I don't yet own a boat so I have no idea if any of the stuff I've listed above works. I've read about SeaClear and it looks nice so I'm going to try that when I finally do get something to sail. Hopefully this summer. A client of mine has a 45' Sabre and he uses a computer with a remote display to handle all of his chartplotting and stuff. The one time I've been out on his boat it seemed to work great. Wish I could remember the program he was using. I do know he was running XP Pro.
Tom