the
Guild Wars 2 system requirements says "iQ6400 / Phenom Q9650, 4Gb, GTS450 2G/5670 1G" which today is a mid-range build / a relatively low end card. But, with your budget you can far surpass that - what I would get:
PCPartPicker part list /
Price breakdown by merchant /
BenchmarksCPU: Intel Core i5-2500K 3.3GHz Quad-Core Processor ($169.99 @ Microcenter)
CPU Cooler: Cooler Master Hyper 212 Plus 76.8 CFM Sleeve Bearing CPU Cooler ($19.99 @ Newegg)
Motherboard: Biostar TZ77XE3 ATX LGA1155 Motherboard ($137.55 @ Newegg)
Memory: G.Skill Sniper Series 8GB (2 x 4GB) DDR3-1866 Memory ($59.99 @ Newegg)
Hard Drive: Samsung Spinpoint F3 1TB 3.5" 7200RPM Internal Hard Drive ($109.99 @ Newegg)
Video Card: Gigabyte Radeon HD 7950 3GB Video Card ($399.98 @ NCIX US)
Case: Cooler Master HAF 912 ATX Mid Tower Case ($52.99 @ SuperBiiz)
Power Supply: Corsair 650W ATX12V / EPS12V Power Supply ($69.99 @ Newegg)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer ($16.99 @ SuperBiiz)
Total (before mail-in rebates): $1097.46
Mail-in Rebates: $-30.00
Total: $1067.46
(Using your selected merchants and only including nearby in-store pickup prices)
Lowest Possible Total: $1037.46
(Prices include shipping and discounts when available.)(Generated by PCPartPicker 2012-05-20 15:52 EDT-0400)This would pretty much make every game out there run very nicely @ 1080. Standard i5-2500k+hyper 212, that biostar is the best Z77 bang-per-buck, 13-phase power & sli/crossfire for $140

, the gskill sniper, high quality can OC at 1:1 or less, Corsair TX650 was a good price / quality point, same w/ the HAF912 nice case to build with, roomy, clean & cool. 7950, expensive but you get what you pay for. The 560ti-448 is a good choice too if you want to have below $1k.
Well hope it gives you some ideas.
cheers!