RiffWorks

I have been using this software since the end of last year and already I have played and recorded more guitar than in the previous 5 years. Not only is Riffworks easy to master and so straight-forward as to be useable by anybody, it is designed to allow your creativity to flow rather than worrying about learning some complicated DAW application. When I had some minor issues, the team at Sonoma (who actively monitor and participate in the support forums) walked me through it and later even released an update to fix another minor issue. Designed, coded and used by both Mac and PC users, support (if you need it) isn't far away.
Riffworks has built in drummer backups, rewire capability (whatever that is!), REX player, many cool effects, and the ability to upload and podcast your stuff so others can work on it as well. Too cool. For the money, you can't get more bang-for-buck than this anywhere, period.