"White Christmas" was written by Irving Berlin in 1940 for the movie "Holiday Inn", and was made popular by Bing Crosby. This song is probably to most popular Holiday song ever written -- one that all aspiring composers wish they could replicate.
For this duet, I borrowed a little bit from my collaboration with Bob Walters of the US Air Force Band back in the '60s. You can see/hear that arrangement at:
http://www.notation.com/vb-forum/showthread.php?t=3110
Ralph Rayner