I've been using Linux full time since Ubuntu 4.06, which I guess was over 4 years ago. It works well for me. The only reason I keep Windows around is for games, and for work purposes (I am a games developer, and most development tools are for Windows).
Oh, and to mount a drive in dosbox, you would simply do this:
mount c /home/toadofsky (or whatever your username is)
And the best source of information is Google. Given the amount of people using Ubuntu, support is usually a quick search away. But it will usually take you to wiki.ubuntu.com