In a dutch oven or large, heavy pot, cook beef over medium-high heat about 5 minutes, or until browned, stirring to crumble. Stir in seasoning. Remove pot from heat. Remove beef and set aside. In the same pot, cook macaroni over high heat, according to package directions. Drain. Reduce heat to low. Combine milk and cheese-sauce mix in pot. Return macaroni and beef to pot, stir well, and cook until reheated, approximately 5 minutes. Stir in cheese and tomatoes and serve.