This has surely got to be the emotional climax of the prequels. (or the saga, bar the redemption scene in ROTJ) So it's only natural to assume that the music that accompanies this sequence will be very moving and dramatic. I imagine this will be the most talked about scene in EPIII soon. Despite the Love theme in AOTC being for Anakin/Padme's romance, I think it has a epic sadness quality that would fit into the duel nicely. Duel of the Fates would work to, the imperial march, force theme...all could be used! What sort of music would you like to see played? What mood do you think is appropriate? Depending on your point of view, the duel could be all about aggression, the dark side...or about the Force, or about Anakin..or about the power of the light side. In ordinary cases, if good would win (ObiWan kills Anakin) triumphant music would play, but that wouldn't seem to fit here.