First, I'd like to acknowledge your joke. I'll chime in (much like the voice directions do while you're trying to enjoy your music
You're not going to believe this until you try it, but the answer is going into Preferences and selecting 'Turn off sound'
I, like you (I assume), selected the 910 b/c of the MP3 player and 20GB HDD. Then after the newness wore off I was SO FRUSTRATED when the voice directions would interrupt my music. I thought I'd tried everything, and selecting 'Turn off sound' made no sense b/c "obviously" if the sound is turned off then the music won't play. Well, that is NOT THE CASE. With "the sound turned off" the music still plays and the blue tooth phone capability still works. The only sound that is turned off is the voice directions. Imagine that!