On Newegg this is coming to around $1100. I just want to play SC2 on medium settings, maybe high if I'm feeling up to it. Maybe also Battlefield 3, on medium. Thanks for a checkup! My main concern is that there's some compatibility issue.
You can definitely run starcraft 2 on maxed out settings with a GTX 560. I have a Radeon 5770 which is way inferior to a GTX 560 and I can still run SC2 on ultra with 30+ fps at 1920 x 1080, but I play on high with ~50 fps.
An i5 2500 and a GTx 560 will easily max out bf3, d3 and perform very well in current games.