It's probably Trans Siberian Orchestra. I love them! They use choir music and instrumentals.
I know what album that song is on. The album is called Christmas Eve and Other Stories. However, I can't remember what the name of the actual song is. It's one of these (I took out the songs on the album I know for sure isn't the song your talking about):
An Angel Came Down
O Come All Ye Faithful/O Holy Night
A Star To Follow
First Snow
The Silent Nutcracker
The Prince Of Peace
Good King Joy
Ornament
The First Noel
Old City Bar
Promises To Keep
This Christmas Day
An Angel Returned
O Holy Night
God Rest Ye Merry Gentlemen
It is not good for all our wishes to be filled; thru sickness we recognize the value of health; thru evil, the value of good; thru hunger, the value of food; thru exertion, the value of rest.