Yeah I'm definitely all for NVidia. Been green team since I can remember. But AMD is far better priced and if OP is running 1080p then one GPU is more than enough. Amazon has some great prices to check out. I would recommend a 770 as a single gpu for that build.
My PC is almost identical to that build (i5-3570K, 8GB Corsair Vengeance, Z-Series Gigabyte M/B) except I have a 128GB Transcend SSD and a Powercolor HD7970. I can testify that it kicks ass like I never imagined. I've played Crysis 3, Far Cry 3, Bioshock Infinite, Tomb Raider, The Witcher 2 and a heavily modded Skyrim recently all at max visual settings with excellent framerates. This is on a 27" Samsung LCD at HD resolution. The 3GB video memory will come in very handy when Battlefield 4 and the slew of other 'next gen' PC games release, like Watch Dogs, Project Cars, Titanfall, GTA V etc. And because the PS4 and Xbone use AMD hardware, it's quite likely that most future PC games will be optimised for AMD graphics cards.