Get the 460.
Also, the 580 is a pile of crap. It gets about the same FPS as a 560, just a little bit better on other things that don't matter. You're basically spending $9001 more for a +20 to the title.
Here's a full-on PC guide just in case anybody else wants one.
[img]https://i1002.photobucke*****m/albums/af150/The_FalconO6/CurrentLogicalPCBuyingGuide/Guide.png[/img]