Cook pasta according to package directions.
In a skillet, cook beef and onion over medium heat until meat is no longer pink and drain.
Add the cheese, salsa, tomatoes and taco seasoning.
Drain pasta and stir into beef mixture.
Transfer to a greased 11-in. x 7-in. x 2-in. baking dish.
Cover and bake at 350° for 20 minutes.
Uncover and sprinkle with tortilla chips.
Bake 10 minutes longer or until heated through.
