8600GT VS 9600GT PERFORMANCE

What is stronger and more powerfull because i currently have an XFX nVidia 8600GT XXX Superclocked Edition and my friend said "Your a heavy gamer and i have a better graphics card than you want to swop" and i replyed let me think about it and now im deciding so which one is better from most people iv heard from my 8600gt is quite a good card and is know as a Mid-ranged card
so please tell me what is better.