I'm not a great musician, but I always have fun trying to take a stab at things, and one of the main things I've noticed has gone under the radar (so to speak) in modding was the in-game music. Don't get me wrong, I think Stardock's done a great job, but it's always nice to have added variety. So, does anyone know of any good computer music creation programs, preferably free or at least relatively cheap (<$50 would be nice) that would let me take a stab at adding my own soundtrack to the game? Something like a computer synthesizer, that would allow me to set the "instrument" and play a tune and save it if it's any good?

Thanks for any help you can offer!