>What would you do to build muscle?
Lift heavy. Use workouts like PS, Pyramids, S&H, Gym Styles. It also pays to do some endurance work -- PH, ME, PP/SS, MM. Have an eating plan that will provide you with the energy you need for the workouts and support recovery.
>What would you do to lean out?
Cardio (step aerobics, kickboxing, running, etc.), interval training (IMAXes), cross training (Bootcamp, high step workouts, C&W, Circuit Max). Cut some calories and carbs. Not so much; just enough to make the body slowly burn its fat stores.
Pinky