Sorry but no, you need an identical CPU to the one you are using. You would see a much bigger performance boost if you bought a new GFX card instead anyway. Multi CPU and dual core support is scant at the moment anyway and it is unlikely that you would even notice a difference if you added a second CPU. It only gives advantage if the software knows what to do with it and at present, even if you have a dual core ready OS, any games you play likely do not support it anyway. To my knowledge there are VERY few games that support even dual core atm, let alone 4 cpus. Wait a few months for ATI to release its Direct X 10 GFX card range so that prices of Nvidia's stuff comes down then get the best value DX10 card you can.