In a heavy medium saucepan, combine sugar and corn syrup over medium-high heat; stir frequently until mixture boils. Allow to boil 30 seconds without stirring. Remove from heat and stir in peanut butter. Pour peanut butter mixture over cereal; stir until well blended. Press mixture into a 13 x9 baking pan; cool. Cut into 4 x1 bars. Combine next 2 ingredients. Dip half of each bar into dark chocolate mixture; place on wax paper until chocolate hardens. Drizzle white chocolate over dark chocolate and return to wax paper to harden.