BRING water to boil in large skillet on medium-high heat. Stir in Macaroni; cover. Simmer on medium-low heat 10 min. or until macaroni is tender and most of the water is absorbed. Stir in contents of Cheese Pouch. Remove from heat; set aside.
HEAT medium nonstick skillet on medium heat. Add tomatoes and sugar; cook and stir 2 min. or until tomatoes are softened. Spoon over macaroni and cheese. Remove from heat.
TOP with mozzarella and oregano; cover. Let stand 5 min. or until cheese is melted.