(FILM) Though this Sundance favorite treads along a troubling moral tightrope, it also offers an exhilarating twist on the "underdog with a dream" scenario. And unlike most music-related stories, this story of a Memphis pimp on the lookout for hiphop redemption centers on the writing and recording process, not a big climactic performance. And, shitlords, Ludacris is in it! (See Movie Times, p. 91, for info.) SEAN NELSON