Just a quick message to say i buy Computer Music magazine and that always has a tonne of very usable samples on there, i find the single hits more useable as i can then stick the wav's in to my sampler to then create beats from.
The garage band drum samples are quite good, but very limited, you can create you're own kit on the program though and if you set an individual hit to an individual track then you get complete freedom to EQ and level that hit to the ends of the earth, its time consuming and you'll probably want a MIDI controller to "type" out your beats initially but its very rewarding and the tracks can sound very faithful to real drums, or if you program some IDM and Breakbeat like me a simple stereo editer is all you need, for PC soundforge for MAC i use Audacity.