Its not good just to throw a new set of pad on a car without resurfacing the rotors. Your rotors and pad need to be both done at the same time because pad material actually transfer to the rotor, making a better friction surface, which means better stopping. If you replace just the pads, its a different material then the material that was already transferd over to the rotor, making the friction surfaces different and actually reducing stopping power. You're rotors will also start to glaze if you don't turn them, which means they get really smooth, and this can also cause them to squeak and not stop as well..
done just keep replacing pad or adding that anti squeal crap..go find the source of the problem and then you won't have to deal with it again..