Jam

It sounds to me as though your new to the business of composing music with computers. In that case I would not reccomend getting Cakewalk as it will take you a long time to get to know how to use it. I would suggest Reason or FL Studio (or both), they are both easy to use, it's just a matter of reading the tutorials provided with the software. In any case, you're not going to master it over night, but these tools make composing a lot easier.