I am not even going to ask what your OS is because I can tell you that you will see a smoother performance with 2GB of RAM. What is your RAM at the moment? DDR2 800?
I think your CPU is decent. It will hold the GPU back but all CPUs are at the moment. The question is to what degree, not will it or will it not. I heard somewhere that you have to OC Intel's quads to 3.2GHz in order to remove bottle necking. I am not sure how true that is but faster CPUs do bring overall better video performance.
I think you are set though. Adding an extra gig of DDR2 will help you out for sure.