Empty pasta mix into 3-quart saucepan 2/3 full of boiling water. Gently boil about 12 minutes, stirring occasionally.
Drain pasta; rinse in cold water. Shake to drain.
Stir together Seasoning mix, sour cream, water and chili powder in large bowl. Stir in pasta-vegetable mixture, tomatoes, bell pepper and onion. Stir in chicken.
Line serving plate with tortilla chips. Mound salad onto chips; sprinkle with Cheddar cheese. Serve with salsa. Refrigerate any remaining salad.