In a large skillet, brown the meat until no longer pink, drain grease, and return to pan. Meanwhile, boil water and cook pasta shells until al dente, then drain and set aside. To ground beef, add tomato sauce and taco seasoning, and stir until well blended. Bring to a boil. Add all remaining ingredients and cook for 5 minutes. Serve with toppings such as sour cream, taco sauce, tomatoes, onions, taco sauce, or whatever your heart desires.