There are a few, but they might be a bit complicated (music programs tend to be)
You have Famitracker, for nintendo like music
This one is pretty simple, but loops tend to click unless you edit them.
Anvil Studio, for Midi files (I wouldn't reccomend midis, as they tend not to sound very good.)
SFXR, for sound effects (Generates oldschool arcade sound effect)
If you can find something to convert XM files to MP3/wav, you can use tracker programs (such as milkytracker) (XM files are like Midis on steroids, and are actually good. If converted to MP3, you can have relatively easy to make music pretty quick)
And, for sound/song editing, get Audacity. It's the general purpose thing for audio editing.