What is a good free music creation program? I have a few stipulations, please read details.?

I don't have a MIDI controller or any instruments/amplifiers/rack components but I need to compose a couple songs for a Flash game I've written. The program doesn't have to have all the bells and whistles but it needs to be understandable and easy to use. I've tried Reaper, LMMS, Magix, and a few others I found with google but they all require you to have either a MIDI controller or an instrument that you plug into your computer so I can't use any of them. The only one that worked without an external device was LMMS but the sound was distorted and several octaves below the notes I wanted. What would be ideal would be a program that was similar in functionality to the old school song creator on MarioPaint (SNES) but it needs to have a *little* more variety than that. A programmable virtual Casio keyboard would be perfectly fine but I can't seem to find anything that doesn't require a lot of VST plugins or that will simply play the notes through the speakers or put them in .mp3 format. Thanks in advance for your help.