Ann, the MIDI in the Mudcat MIDI section sounds good, but it has one mistake. To fit the rhythm of the song the words "...fill the..." in the last line of each verse need to be eighth notes

Actually, that's not a mistake... I made that change deliberately, and sent an updated version to MMario (after posting the change here, to see if it sounded right to others).

For the longest time, I couldn't figure out why people kept telling me there was an extra beat in the last line ("Raise all your voices, may sweet song fill the air."). Then (after singing the song over, and over, and over, both with and without the "extra" syllable) I realized that I was naturally singing the song in the rhythm as it is now -- or something very, very close to it. What I'm actually singing, on the three syllables of "...voic-es, fill..." (and "...voic-es, may...") is: quarter note--dotted eighth note--sixteenth rest--quarter note.

But that looks really fussy and confusing on a score, particularly if it's to be printed out and handed around to people at a holiday sing-along where not everyone is comfortable reading music. Depending on what instrument patch you stick at the beginning of the staff, the difference between the rhythm as I outlined it above and three quarter notes is barely noticable... so for print-out, I opted for the simpler-looking version, trusting any would-be singer to use the score only as a guide, and sing it in a way that comes naturally out of her or his mouth...