QUOTE(anacrusis @ Apr 17 2008, 04:48 PM)

petrat, even Trevor Pinnock started out on the piano and organ first....
I think Petrat meant people for whom harpsichord had replaced piano, or who study it seriously alongside piano, as opposed to people who are primarily pianists but who occasionally play the harpsichord for some reason.
Most organists (and I would expect most/all harpsichordists) start on piano, but there's a difference between an actual organist and a pianist-who-plays-the-organ.
A pianist is going to be able to sit down at any other keyboard instrument and play something. But he won't have the instrument-specific technique of someone who studies the instrument.
Organists who don't keep going with piano can, of course, play things on the piano when they need to. But you can usually tell from the way they play that they're organists not pianists.
In general, if you can't find a harpsichord specialist and you need to find a stray keyboard player to accompany someone on harpsichord, you're better off with an organist than a pianist because there's actually more simlarity between organ and harpsichord than there is between piano and harpshichord (in terms of playing them, not in terms of how they're constructed).
An organist friend of mine played harpsichord for me for a bunch of baroque flute and recorder stuff and was really great at it. It was a two manual harpsichord, with a couple of different stops, and he knew what to do with it and how to vary the dynamics by changing stops or switching manuals.
T.