I have a credit with a music store (Sam Ash) and no longer have a MIDI keyboard. I just bought Logic Pro 9. My computer is an iMac 10.1 4 ram which has 4 USB ports one of which is unoccupied. I take it I don't need a MIDI interface if I am only using samples etc. (I will probably get rid of my venerable Roland external sound modules which I haven't used in some years.) My question concerns whether I need a MIDI interface and whether the keyboard will work directly with just samples?