Get something like this :
Processor : AMD Phenom II 960T
Motherboard : ASUS M5A97
Ram : 8GB DDR3-1600
Graphics card : Radeon 6850
PSU : Any good 600w
HDD : Seagate 1TB 7200rpm
Case : HAF 912
This costs around $650 so you can buy a cheap CD drive and any other things you want.