Bring the water to a boil in a medium to large pot. Add 1 tablespoon salt. Then add 8 oz. uncooked macaroni. Allow this to cook until almost done--al dente. Drain with a colander in the sink, leaving the cooked macaroni in the colander, continuing to drain over the pot. Now make your cheese sauce: melt the 3 tablespoons of butter or margarine in a medium saucepan over low heat. Add the flour slowly, stirring continuously, until a "dough" called a roux is formed. Remove from heat, and add the 1/2 teaspoon salt, 2 cups milk, and 2 cups cubed Velveeta cheese. Return the saucepan to the stove and cook the cheese sauce, stirring constantly until it is smooth and all the cheese is melted and incorporated into the sauce. Go to the pot with the colander of macaroni on top. Lift the colander while you pour any drained water down the sink. Now empty the colander of macaroni into the pot and pour the cheese sauce on top of it. Lightly stir the cheese sauce and macaroni together until all macaroni it coated with sauce. Pour into an appropriate serving bowl. Call the kids--they love this type of macaroni!