im not sure what is ur budget , but i'll suggest these if you got high budgets
CPU : Intel I5-2500 ( non K version if u dont intend to do overclocking in the future )
Motherboard : MSI P67A-C45 B3 ( if u not going to SLI in the future) / MSI P67A-GD65 B3 ( for SLI In future ) i recommend these since these motherboard are cheapest and high performance for me at least
GPU ( if you have budgets left) : either GTX 460 / GTX 560 , if u are in low budget , stick with gts 450 / gtx 550
and you need to change your ram too since the new motherboard doesnt support old DDR2 rams....
oh yeah , and you need a new PSU as well....get this one : SILVERSTONE Strider Essential series ST50F-ES 500W since the graphic card's power requirement need at least 450w or above..