As the others say, Fruity Loops (FL Studio) is the simplest way to go. Its very simple to start yet you can make it as profesional as you want as you go along. Dance EJay or Techno Ejay is also a good way to go to start off with. Again simple with a nice easy interface but you can do some cool things with it. Cubase, Logic, Reason and Ableton Live require a considerable amount of patience and know how before you get the results you require. So best start with something easy first.