two tips from personal experience:
1.) GTX 560Ti is a great value, the card has a good speed and is relatively cheap, made only good experience with it
2.) i5 2500K, runs at 3,3ghz stock, equipped it with a Scythe Nasya (40$) and running it at 4,3 ghz atm, capable of more easily, 4,5 ghz still runs stables. So you can get about 1ghz for free