ah, flight sims do have a couple of requirements that other games dont. i know for a fact that they dont support SLI/crossfire, and they are also very CPU intensive (so you might want to up the cooler and back the graphics down to the 560Ti). however, i'm not sure if they make use of hyperthreading.
just a quick question. are you planning on going for a build with 3 or more monitors? if so then ATI is the only route you can take, but if not then its far better to go with Nvidia
its probably best to sell the 460 on. its massive overkill for a physX card, which is all you could do with it