Looking good, though I would upgrade the RAM to 8GB if possible. Also, take a look at this motherboard: http://www.newegg.com/Product/Product.aspx?Item=13-157-... , it has no 1 star reviews, and it is from ASRock, which has really become a good manufacturer this hardware generation. It also supports PCI-E 3.0 which will be useful in the future if you choose to upgrade.
Yeah, I'm pretty sure the general consensus from everyone is going to be that if you can squeeze in an i5-2500K, a 560ti (or 6950), and 8GB of RAM you'll have a great machine. Those three parts move you out of the "budget build" range and into the low-end of the "enthusiast" range. It'll last you longer before you need to upgrade.