In all likeliness, I guess you should expect somewhere around 40+ FPS on medium or high presets on that resolution. Without AA and AF. Though I maybe understating what a 5770 capable of. That's the best bet I could give you. That's enough to warrant playability.
And your system is quite balanced, I must say.
To get 60+ Ultra, I guess you'll need an additional core and a much more substantial GPU.