Preheat oven to 400°F. Prepare macaroni dinner as directed on package. While macaroni is cooking, brown meat; drain. Add taco seasoning mix and water to meat; simmer 5 minutes. Stir sour cream into macaroni dinner. Spoon half of the macaroni mixture into 8-inch square or 9-inch round baking dish; top with the meat mixture, 1 cup of the cheese and remaining macaroni mixture. Cover with aluminum foil. Bake 15 minutes. Top with salsa and remaining cheese. Bake, uncovered, an additional 5 minutes or until cheese is melted.