With no problem. However you might experience "bottlenecking" from the CPU.
Bottlenecking is when one component doesn't allow the other to run at its' full potential. Like a too slow CPU (as in your case), won't allow the GPU to run at 100%. It could also be the other way around. http://www.youtube.com/watch?v=TGdo75gasaQ
- Here is a more proffesional explanation.
Still upgrading the GPU would serve as a great increase of performance in your games.