Upgrade from a GTX 460?

Hey gang,Ok so I am getting the itch. The same itch I seem to get every year or two at the max, to do some hardware upgrades.I am pretty happy with my current system, although I get a little jealous - and tempted, when I read of other's overclock with the SB chips. My system is currently running rock solid at 4.1 ghz, and performance in FSX is pretty dang good.I run FSX with the following addons:FS Genesis MeshUTX USAGEX NAREX2 ODI run my REX clouds at HD, with the 2048 resolution setting. Looks beautiful.Ok, so I know I will be building a new system before too long - at this point though, figured best to wait for Ivy Bridge and just skip Sandy Bridge.So that brings me to the video card. I currently have an EVGA GTX460 SSC 1gb video card. This is a factory overclocked card.I am considering upgrading to say either the GTX 570, or GTX 580. Now I know FSX itself will not benefit greatly from a vid card upgrade, but thinking it may help with say the REX clouds? Also now that I run Flight as well, I know it will benefit from it also.I would sure appreciate any feedback on going from this 460 to a 570 or 580.Thanks,