In A Saucepan, Brown Ground Beef; Drain. Add Salsa, Mayonnaise And Chili Powder; Mix Well. In An Ungreased 2-Qt. Baking Dish, Layer Half Of The Meat Mixture, Chips And Cheeses. Repeat Layers. Bake, Uncovered, At 350 Degrees F For 20-25 Minutes Or Until Heated Through. Just Before Serving, Top With Tomato And Lettuce.