I'm another writer that can't write in that "silence" that people seem to keep talking about. I need the music to tune out the other noises: TV, radio, lawnmowers, the 'clackity-clack' of the wife's keyboard on the other side of the room....
I've got playlists put together for the various pieces I'm working on, ranging from soundtrack, to classical, solo piano, acoustic guitar... to some symphonic rock, bit of alternative, a dash of techno... Whatever I can find that either fills the mood for a section, or serves to sum up a character. Other times, I need something to put the mind into that fat, sloppy delta-wave and let the ideas come a-rollin' on through...
Lately, the ritual has been starting the playlist with a character piece, or the story theme, and then letting it shuffle out and see where the tunes take me.