Just out of curiosity, how come you stuck with Sandy Bridge now that Ivy Bridge is readily available? You can get the i5 3570K for just $10 more than the 2500K, and an Intel Z77 board for $5 cheaper. Since it doesn't sound like you're going to be overclocking, for about the same price you get the latest and greatest CPU/mobo combo and it future-proofs you a little more than going with Sandy Bridge.
3570K CPU - http://www.newegg.com/Product/Product.a ... 6819116504
Z77 Mobo - http://www.newegg.com/Product/Product.a ... 6813121606
You'll want a fairly decent video card, both ATI and nVidia have good cards that can be had for pretty cheap, really depends on personal preference. ATI 7850s can be had in the $250 range, GTX 560s are also in the $200-300 range, both would be decent for all but the newest and most graphics intensive games, but are getting a bit old. If you can bump up to $400-450 for a video card, you can get either an ATI 7970 or the GTX 670, both are excellent for any game on the market today and will still be good for a couple years.