Good background music does add to the game's atmosphere.  But, if a game is really good, I play it anyway and just ignore the music.
DD has an outstanding soundtrack.. In fact, I got a couple of people I know, into DD because of its music.  All I did was send them a couple of the tracks from the game, and they ended up trying out DD.  And of course, they ended up loving the game as a whole! [insert gollum's psychotic laughter here..].  They originally didn't want to play the game because some idiots told them the game is not good. Ha! Showed them!  <img src="/ubbthreads/images/graemlins/badsmile2.gif" alt="" />