What music programs are there on the computer to compose music?
It depends what way exactly you want to write. If you want to sequence the notes in the computer, your best bet is a MIDI sequencer. Cakewalk is a good one, I’m not familiar with other ones but there’s probably a cheaper alternative. The sequencer does not produce any sounds, however, so you’ll need a synthesizer if you want to get sounds better than your sound card can produce. I have a Roland JV-1010 and would recommend it if you want a synth but it doesn’t have to be professional sounding. Another way is with something like Fruity Loops, but you can only write techno-ish music on that. Or you can record live instruments into your computer with a good recording setup and something like Audacity or Cool Edit Pro. There is other good software, just look around and see what appeals to you.