That's Hallelujah, written by Leonard Cohen. But if you want to hear it sung beautifully, listen to Rufus Wainwright do it, it's on the Shrek soundtrack.

On a side note, i don't know why i keep posting so many lyrics, i guess i'm going through one of those phases. I think i'm rediscovering good songs that i haven't listened to in a while.

-Lara