Thanks for your comment Pianowolfi. I found a wonderful piece of software called Pianoteq....I downloaded the demo version and made a new version of "Suite Triumph" using it. Since it is the demo version it takes out a handful of black notes, but amusingly I don't think it is even noticable. There's one climactic melody note in one part that is omitted, that's all I noticed. *edit* now that I know which black notes are omitted, there are actually quite a few places that sound odd.
Anyway, what a difference! I think I shall start making all my recordings with midi and making conversions with this software. Have a listen...