BROWN meat in large nonstick skillet on medium-high heat; drain. Add seasoning mix, water and Macaroni; mix lightly. Bring to boil; cover. Simmer on medium-low heat 7 min. or until macaroni is tender and liquid is almost completely absorbed.
STIR in sour cream and Cheese Sauce Mix until blended.
TOP with tomatoes, lettuce and tortilla chips.