Re: GTX 470 on Core 2 Quad Q 8200
Are you willing to overclock?
I went from a C2D E8500 @ 3.8Ghz + HD 4870 512 mb to a Phenom 2 BE955 @ 3.6 + a 470, and the difference is very noticeable, huge in some games.
I have no idea what your budget is, but I would grab the 470, test with the C2Q at stock settings, then again with a nice overclock, and note the difference. If the overclock shows huge gains, you know you'll benefit from a faster proc. If not, save your money.
I don't have info available as I'm at work, but the 400Mhz oc on my proc gave me some reasonably decent gains.