I’ve spent a bit of time messing around with Garageband in the stores (before I bought my Mac). David Jones in Sydney has a machine setup with a MIDI USB keyboard where one can use Garageband, etc.
Since I bought my Mac (which came with iLife ‘05), I’ve been wanting to use Garageband. So.. I just ordered an M-Audio 49E keyboard.
It should arrive next week, and then I get to have some fun.