Well, you may want to invest in a Hip-Hop expansion board. This board has all of the possible noises, shouts, screams and countoffs you could possibly want and more.

I also got a SC880 Modules for $350 a couple of months ago. Best investment in my studio yet. It has a huge GS extension. Some of the sounds in the Roland SC880 outclass a stock XP or JV. Really check it out. It's only about $50 more than an expansion board.