As far as I know the Otterbox case is not water proof or dust proof for that matter ( i read of some one using it in his pocket and getting dust behind the screen covering). The Lifeproof case is water and dust proof and is less bulky. It is a really great case and they sell it at best buy or online at iPhone 4/4S Case - Gen 2 - LifeProof Apple Cases - LifeProof Store :: LifeProof Cases
I'm getting the white one. Those rock! Thank you soooo much!!