I use Noteworthy Composer for creating a score. It will also create a midi file. Add chords by using insert/text above or below the staff just before the note - not very difficult.

You can create an abc file using another program abc2nwc . It will also convert an abc file to a nwc file - very helpful when you have to start with an abc file. To play the abc file I use AbcMus .

I can also create a midi file from AbcMus. In AbcMus you can also adjust the tempo, rhythm (reel, jig, waltz, etc), and if you have chords in the orginal nwc file they will translate to the abc file and the midi created with AbcMus will also play the chords along with the melody.

For me, this is a great combination. I can go from an abc file to a complete printed score in just a few minutes. That's quite useful for fiddle tunes which are often posted as abc files.

Cheers, S. in Seattle