I have just about every Christmas song there is, recorded from a wide variety of artists:
Trans-Siberian Orchestra
Mannheim Steamroller
John Williams
Enya
Garth Brooks
The Chipmunks
Lonestar
Amy Grant
Michael W. Smith
Third Day
Casting Crowns
Relient K
Jars of Clay
Neil Diamond
Harry Connick Jr.
Frank Sinatra
Nat King Cole
Irving Berlin
Gene Autry
Paul McCartney
Billy Idol (yes he put out a Christmas album)
Elvis Presley
Jimmy Buffett
Alabama
...and various other music from artists I can't remember.
I store all my music (54 GB-10,000 songs) on external hard drive and have a Christmas music folder separate from all my artists folders and it is around 2 GB.
I usually purchase at least one newly released Christmas album every year and this year it was the Casting Crowns album.
"Little Drummer Boy" is my favorite Christmas song and the two groups that have made the best recent versions that I listen too is by Lonestar and Jars of Clay