Before ''Gigli'' earned the title of the summer's biggest turkey (gobble, gobble), there was From Justin to Kelly, in which Kelly Clarkson, Justin Guarini, and Justin's hair fall in love in Miami over spring break. The brisk musical isn't so much an affront to humanity as it is derivative, cribbing from such works as ''Grease,'' ''You've Got Mail,'' ''Casablanca,'' ''West Side Story,'' ''The Women,'' and the entire Annette Funicello oeuvre. Kelly's voice, as usual, acquits itself beautifully; Justin's hair, not so much. EXTRAS Giggly commentary from Kelly, Justin, and director Robert Iscove, as well as two additional bland songs wisely omitted from the theatrical version.

