Preheat your oven to 400 degrees.  Prepare the Velveeta  dinner as directed on the box.  While the macaroni is cooking, brown the meat and drain.  Add the taco seasoning to the meat. Mix well.  Add water.  Stir and simmer for 5 minutes.  Stir sour cream into the finished macaroni and cheese Velveeta dinner.  Spoon half of the macaroni mixture into an 8 in sq baking dish.  Top it with a layer of meat mixture and cheese.  Repeat layers again, then bake for 15 minutes approx.  Top with the salsa and remaining cheese and crushed tortilla chips.  Then bake an additional 5 to 10 minutes.