Right now my CPU is a Intel Pentium D CPU 2.66GHz I was thinking of upgrading to a AMD Phenom II X4 3.4GHz CPU for around $165. My video card is a GeForce 8600 GT. I would like to know, first, would it be a better idea to upgrade my CPU compared to a GPU? If the quad is a good choice, does anyone have an idea of what my framerate would be with the "recommended" CPU, but also the "minimum" required GPU on a game such as Bad Company 2? Sorry if i didn't make sense, I'm not much of a computer person.
The CPU switch would require new RAM and motherboard as well.
Look up your motherboard for a CPU support list. A Core 2 Duo would be a huge improvement if supported.