Hi,
Definitely get your old A500 going! Always worth it, getting an old machine going again!
As for OctaMED, it's still alive and well - there's a PC version now, renamed back to MED, and it's pretty well featured if you're used to the SoundTracker way of creating music. Web site is
here, a trial is available for download and it's pretty inexpensive to get the full version.
Plus it'll load Amiga OctaMED/MED files, as well as a variety of MOD formats.
- Ali