I play on high with 55-60 fps on a comp that cost me about 900 usd (700 euro) overall - with 560ti gpu (bought 1,5 years ago), amd fx8370 cpu. Well, not when there's a zerg like the Volan event. Then I'm down to 25 fps.
If you head over to the Computer sub-forums here on MMO-C as well, there are more guides and even a list of sample builds. There are also tons of friendly and helpful people there who will help you with your build and any questions you have. Also there is a sticky that you can fill out and post and asks you things like what resolution you want, what games you want to play, what peripherals you need, do you need an OS. Without knowing those things it is really hard to give you any sort of advice as adding a monitor and an OS adds $200 to the build, so can;t put something together without knowing that info.
Also, @Mifuyne saying a 3570k and a 660ti, with an SSD on that budget? You are nuts. There isn't room there. My general recommendation for SSD is if the total budget is under $800 it is not worth it. That money is much better spent on CPU/GPU. An SSD does nothing for gaming. It will not increase your FPS or make your game look prettier. It is a luxury and really nice to have, but on an $800 budget, I'd rather spend that money elsewhere.