If you keep running out of ram, yes, if not... Well you can since ram is so dirt cheap now.
GPU, honestly that is one of the most powerful dx10 gpus out, if you want dx11, you can upgrade, if not I would wait for the rest of the line up of kepler and southern islands to come out and then ask again.
But if all you play is css, that game should not stress any of it and it only runs in dx9c