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