Cook rice in water as directed on package, omitting margarine and salt.
Meanwhile, place 2 tablespoons of the taco seasoning mix in plastic bag or medium bowl. Add chicken; seal bag and shake or stir to coat well.
In large nonstick skillet, combine chicken, tomatoes, ground red pepper and remaining taco seasoning mix; mix well. Bring to a boil. Reduce heat to medium-low; cover tightly and simmer 8 to 10 minutes or until chicken is no longer pink, stirring once. Serve over rice. If desired, top with nonfat sour cream and chopped fresh cilantro.