No one can tell you what GW2 is going to require for max settings. Ive been trying to get that from someone at the tradeshows with no luck. The 460 is a pretty strong card at 1920x1080, but not superb at it. Its really an upper-midrange card.
Without a good power supply, those parts are just a paperweight. You have to figure out your graphics card situation because that dictates how powerful of a PSU you need.
You have a top end CPU mixed with a mid-high graphic card. You could drop to an AMD Phenom IIx4 955/965 system and use the saving to get a 5850 graphics card for better gaming performance. If your plan is to maybe get a second 460 1GB card in a year (when they finally release GW2) then the i5 system is a great idea.