Just built up this system today for a customer. It uses a very nice motherboad from Gigabyte, the GA-880GM-UD2DH. For a top notch system at a great price point, this is currently my pick.
I dropped in an AMD Phenom II processor which can happily run at hugely overclocked speeds with this board. Add 4GB or more of quality DDR3 12800 RAM and you have a great system, rock solid, ready to run Win 7 64-bit at blistering speeds.
Twin SATA II 500GB drives allowed for huge storage but most people would be OK with a single 500GB drive.
Here’s the components I used, add your own DVD drive, case, PSU etc.