+1 To both of the above, would definitely be a nice upgrade, although a motherboard change may be needed, depending on which CPU you get it might not cost much.
You could easily upgrade to something like an i5 4460, i5 2500K and do a nice overclock on it, and it'll boost your performance, although it is an older generation of CPUs, the extra cores will make it seem quite new. Quite a lot of people game on a 2500K still, and the i7, a 2600K I believe. Either of those CPUs can be found for quite a nice price, and give you a great performance boost.