i use a program called tuareg 2.5. it rocks, but it's not really a classic drum machine.... it's a whole lot more.... it's something you'd like if you wanna use samples, loops, etc. you can download it here:
http://www.brambos.com
and then there's another one i use called pc drummer. they have a demo version you can try out:
http://www.pcdrummer.com
give them a shot.
p.s. - i use buzzmachines too, but that program requires some pretty hardcore programming skillz. it's not as intuitive as these other programs, but buzzmachines is still pretty cool.