If the difference comes down to price between Dell and Gateway, then I still don't see where Dell beats out Gateway. For a comparable system, neither really had a significant price advantage over the other.
As far as who's going to last... Dell is pretty strong. They've been stronger, longer than Gateway. Not that Gateway is going anywhere in, let's say, the next 2 years, but if I were to say one of them would go under, I'm afraid it would have to be Gateway.