I don't know if it's been discussed already, but right next to me is the Line6 GuitarPort; probably the most commonly used pre-production tool for guitar.
When it comes down to an armchair rockstar, it's all you need... well GuitarPort, FruityLoops, and Audition.
Seriously. I'm not going to name any names
, but there are (fairly famous) albums out there recorded with just this setup, and you'd never know*..
*Edit: The cymbals are the hardest thing to get to sound right on a computer.