Hello there!  I just wanted to second the voice about the CD-RW.
CDs are very long lasting.  They don't fade or lose information.
In the worst case the disc gets scratched or broken in half.  For both
of these cases I have seen (more or less expensive) places that will
retrieve your information from a unit even in such conditions.

But the good thing about CDs is that you don't even have to let it come
to that: with "raw" (blank) CDs being as cheap as they are now, there
is always financial room to have backup copies of every one of them.
Buy yourself a fire- and heat-proof safe and deposit at least one of
the copies there.

Maybe CDs are not to last as long as paper, but the big advantage of
CDs is the speed with which they reproduce.  Just let us assume CDs
"wear out" every 20 years.  Well, you just will have to make new backups
every 18 or 19 years!  And until then, there will be new media out with
much better and bigger storage.

Already today you can afford DVD-burners.  With much doubt, I would
think, anyone of us can fill a DVD with MIDI files!  With one to two
DVDs that last at least 20 years, do not tell me that that is not an easy,
fast and long-lasting way of storing _data_.  Just make sure you date
the CDs and make a remark on when to re-backup them.

greetings by(e) InK - Ingmar Krause
Victoria, BC, Canada

P.S.  And don't forget about the size of the medium: music stored as
MIDIs on DVDs vs. music stored as holes on paper.