Wait until Haswell comes out and dump your whole system. 2014 maybe.
What a waste.. Your system is running fine for the moment then you could possibly upgrade your cpu and mobo when haswell comes out later this year
For immediate upgrades, you can consider getting a Z77 chipset motherboard and get a i5 3570k. Your graphics card and PSU are solid for at least another year. Also, you might want to get a SSD, best price/ performance boost.
For future upgrades, you can wait for the new Haswell series CPUs to come out (June 2013), then get a new i5-4xxxk CPU and a new motherboard.