Re: drum machine
Depends on your approach. If it's strictly rock, then a good old-school Roland or Alesis (mid-90's) will do quite well. Some of the Korg or Yamaha keyboards have decent drum sounds also.
One of the things that determines a convincing drum sound is dynamics. If it's rat-tat-tat boom-boom-boom all the way through, with no nuance of tone or other changes, then people will notice right away. Use the sequencer of your choice to loosen up the feel, move things ever so slightly ahead of the beat (for energy) or behind it (for an "in the pocket" groove). Don't lock the quantization down too tightly; even the best drummers are still human.