Replace your mobo with a G41 or G45. these are very good mobos with DDR3 1333 OC capable. Buy some good DDR3 1333Mhz Ram sticks (8 GB). C2Q is a overclocking beast and better then Core 2 extreme when overclocked but the stock cooler from intel is hopeless. Buy a nice closed loop dual radiator liquid cooler and aggressively overclock your cpu.
I not very good with computer language, I can understand a lot of it but I really don't want to upgrade anything else so that is why I was wondering if this would be a good card for my machine. I don't have a lot of money and found a good deal on a 660.