As the title suggests this is a moronic question but I thought I'd ask it anyway. I'm looking into getting a Roland MIDI Controller (http://www.musiciansfriend.com/srs7/g=key/search/bigpid/base_id/54345/) to use with, you guessed it: GarageBand. Now there are also some nice keyboards out there I want also. So, as the title suggests, what is the difference between a MIDI Controller and a Keyboard?