If you're worried about your CPU holding your gaming performance back than you should relax.You will gain abosolutely nothing in terms of FPS from upgrading to a new Core i5 or even i7 (unless you play battlefield 3 with 64 people).
But if gaming isn't the reason why you want to upgrade your CPU/MB then you should look into buying a Core i7 and a Z77 motherboard.
The CPU you should buy is the Intel Core i7 3770K
As for the motherboard, if you don't want to skimp on quality and want the best there is (within a reasonable budget) i highly reccomend those two models.
http://us.ncix.com/products/?sku=75125&vpn=GA-Z77X-UP4-TH&manufacture=Gigabyte&promoid=1187
http://www.amazon.com/dp/B0090Z39EA/?tag=pcpapi-20
But if you want to increase your PC's gaming performance then you should upgrade your graphics card setup.
You should either buy a single high end graphics card like this one
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202008&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
Which will increase your PC's Gaming performance by about 50%.
Or if you're an advanced user and use RadeonPRO you should buy two HD 7870's.
http://us.ncix.com/products/?sku=77736&vpn=R7870%20HAWK&manufacture=MSI%2FMicroStar&promoid=1030
They will more than double your PC's gaming performance (in games that support CF).