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