Your processor isn't the thing holding you rig's PC performance back.
Your graphics card is your problem.
I know it's a lot newer than your processor but its really as slow as they get.
If you want to play games made after 2006 you really need a new graphics card.
I highly recommend this one.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202010&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
But if you can't afford it, then buy this one instead
http://www.amazon.com/dp/B009FTWHEO/?tag=pcpapi-20
The first card will increase your FPS in games around 16 times while the second one only about 10 times.
But if you don't want to play games and just want a CPU upgrade (if you're encoding video, photoshoping and doing a lot of other things like that)
then go for those two
http://www.newegg.com/Product/Product.aspx?Item=N82E16819116504&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
http://www.amazon.com/dp/B007KTY4QU/?tag=pcpapi-20
Or if you can't afford spending so much money, go for this combo instead.
http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.1162454&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
if you current RAM is DDR2, you'll need to buy a new RAM kit as well
I highly recommend this one
http://www.amazon.com/dp/B008U92JHK/?tag=pcpapi-20