other suggestions: well, since price is no object, I'd go with 580 GTX's in SLI, that will max out Metro in any aspect, even with DOF on. If you want a more reasonable, but still ludicrous in it's own right, how about crossfiring a pair of 5670's for $160.
That's really stupid. A single 580 is plenty at any res up to 1080p, and a single 580 will even max most games at 2560x1600 (though there are certainly several games that can't quite be maxed by a single 580 at that res - I would know, since I'm running a 30" monitor on a single EVGA superclocked 580). Before spending nearly that much on GPUs, if I were in the situation that the OP was, I would upgrade the monitor (I'll never understand people running $1k of GPUs on a $199 monitor).
Oh, and I agree with everyone above. To truly max stuff, a 6850/460 is the way to go. You could certainly get away with less though if you didn't want to max absolutely everything.