In a 1 1/2 quart casserole, arrange chicken breasts with thicker parts toward outside of the dish. Cover and microwave on high 8-10 minutes, until chicken is thoroughly cooked. Remove chicken to plate and set aside. In the same casserole, combine scallions (onions), pepper, celery and margarine; microwave on high 3-4 minutes, stirring once, until vegetables are tender. Add tomatoes; microwave on high 5-7 minutes, until slightly thickened. Arrange chicken on top of tomato mixture; sprinkle evenly with coarsely crushed taco chips, cheese and olives. Microwave on high 2 minutes, until cheese melts. Serve with rice and a salad.