In reply to Nigel's enquiry about conversion, I have been using Visiv's
Sharp-Eye ( http://www.visiv.co.uk ) for a number of years quite
successfully.  I have scanned several pieces which have subsequently
been converted to Polyphon discs by a friend, and some for use on my
Clavinova.

If the original sheet music is of good quality and of average
complexity, I found Sharp-Eye almost 100% accurate, and corrections
easy to make.  Complex pieces, particularly with unusual 'tuplets, did
cause problems, and I gave up on one piece.  Also, where there is an
extra staff for the voice in a song piece, removing the extra staff is
a bit fiddly.  Otherwise, I have found it to be just about the best
available.  The author has also been helpful on the odd occasions I've
needed help.

On the Comments page of Visiv's website there is a list of conversion
software, with comparisons done by a German magazine in 2001 (obviously
a bit out of date now).

The down-side is its price, currently £133 (GB Pounds), which is a lot
higher than when I bought it several years ago.  There is a 30-day free
trial.  I have no connection with Visiv. I am just a satisfied user.

John Farmer
UK
http://www.musicanic.com