The song was originally done by the Magnetic Fields (Steven Merritt) although I think I prefer the more emotional, sappier version done by Peter Gabriel, which was also used in the series finale of Scrubs.
And, as a bonus, it's fairly easy to sing, and, therefore, ideal for a person with a limited range. Would I dare sing it at my friends' wedding? Honestly? Performing in public scares the heck out of me. But... I'd really love to do something special for them both.