Oh thanks man. I get acapellas from www.acapellas4u.co.uk
and the rest of it from CDs I own. I put them together in Audacity, a free but surprisingly good open-source audio program.
I don't listen to too much rap but most of the rap I do listen to is mainstream stuff. I haven't heard of ANY of those guys you mentioned, but I heard the stuff you made on your band's MySpace and it's awesome so I'll be sure to check those guys out.