Double irony: I just got through watching that episode on DVD (I'm mainlining Numb3rs right now) and frankly, k.d. lang's version is nice, but it wasn't very well used in the episode.
For one, the balance between the singer and the dialog in the scene wasn't well balanced from an editing standpoint, secondly, it didn't seem appropriate to the situation.
Three seasons in and Numb3rs still doesn't really know how to use music, but that's okay. Because it's got David Krumholtz and his geekish good looks working overtime for them.