Amadeus Pro or Garage Band

Hi all,
I have a small project which is completely out of my comfort zone. I need to produce some audio consisting of voices, sound effects and background ambient noise, sort of like a radio play or the Graphic Audio productions. I can source the sound effects and bacground noise easily enough from a google search and my voice will do, but here's the thing: which software would be best to use as a complete newbie? Any pointers would be most appreciated.