Ok this is the best thing that happened to me:
Beatmaker 2 for iPad. It gives you what a mpc does. We are just trying to get the sound level right, so that it sticks out in the mix so the drummer can hear and keep time. He's not used to playing with a loop. Rehearsals sound pretty good, but when you factor in the congregation the sound changes drastically. To remedy that, I.'m thinking about getting a mixer and monitors just for the musicians, independent of the house. I will run a the vocals into the mixer and the keys to the main mix. For a pretty big church you need that independence...starting to realize that more and more.
There's another tool I messed around with on my Mac: Nanostudio. The reviews put it up there with Beatmaker 2...didn't buy it because it was a bit more in price.