Combine chicken, sour cream, soup and cheeses in a large bowl; stir to combine.
Add the noodles and gently stir till coated.
Pour into a greased 9" x13" baking dish.
Mix crackers and margarine; sprinkle over the top, sprinkle with poppy seeds.
Bake at 350�F for 25 to 30 minutes or till crackers are crispy and golden brown and cheese is melted.