There is so much software to produce your own music.
Propellerheads Reason (this one doesn't have VST-support), Steinberg Cubase, Ableton Live (like Lead mentioned), FL Studio or Cakewalk. And there also a lot of so called 'trackers', but they aren't that easy to work with.
I would advise you to download the demo's of the programs I mentioned, and then you can see which program's something for you and ?f you like to produce music. Because it isn't that easy to make a whole track, it takes a lot of practice or you're using Magix Music Maker or something?! :D