1)   Click MusicalKEYS 3
Click MusicalKEYS is a free onscreen MIDI musical keyboard. With 127 different instruments, you can play the best music of your choice. Click MusicalKEYS can record your favorite tunes so that you can replay them later.

 2)   Go Chord Composer 6.12
Go Chord Composer is a composer software with automactic accompaniment function, with Built-in 100 accompaniment styles make it easy for the user to quickly design a perfection song.