Upgrading for CoD

[Cpt_Farrel]

Just a couple of perhaps dumb questions that I would appreciate some help with

I'm considering a computer upgrade for CoD and I'm wondering what the most important upgrade would be... I've got 4gb of RAM and seeing other posts I'm guessing there's not need to upgrade that at the moment.

What about graphics card vs. CPU? I've got an NVIDIA GTX260 and an Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz

Back in the days I used to know about these things but I've lost track completely the last 5 - 10 years...

Thanks in advance!