Lucas said:I'd check out SampleTank free. Or the Reason demo.
Reason is a very versatile program but I think the demo version doesn't let you save, where SampleTank demo does I'm pretty sure.
At least you can get a flavor of what you like this way....
Sample Tank is at.... http://www.ikmultimedia.com/
Reason is here..... http://www.propellerheads.se/
Good luck