DAW: Reaper (Free Unlimited Evaluation Period/$40)
Drums: ToonTrack EZDrummer (or Superior 2.0, though it is closer to $300), XLN Addictive Drums, Steven Slate Drums EX (or Platinum, like Superior 2.0)
Guitar: Line6 PODfarm 2, Overloud TH2, Amplitube, Peavey ReValver as well as numerous free ampsims and impulse loaders (cabinet simulation)
Bass: see Guitar, also Ampeg SVX
Interface: (as with everything else) depends on budget and needs