Linux is great - one my best friends has patches in the next release - but if you're going to do business right now there is still no substitute for Windows, at least in software development for profit.

Linux may eventually be a contender on the desktop - it certainly is already on the server, but someone like IBM needs to put Apple out of their misery and port the Aqua GUI and shell to Linux. Once Linux has as good or better (and standardized) shell it will have a chance on the desktop.

It shouldn't be tough, the Mac already gave up on having it's own kernel and is running on *nix.