wondering if I need more CPU power

I currently have a C2D e6600 OC'd to 3.12ghz and I was wondering if i would see noticeable improvement upgrading to a new board and CPU(i7,i5 or Phenom II). This is assuming the the video card is not a bottleneck. The performance gain in question is related to just gaming. I play current games like BC2, SCII and Just Cause 2. I looked around online and found the answer to be minimal gain but I wanted to see what anyone else had to say.

Well honestly, if you're only gaming, all you really need is a C2D. I can game fine on my C2D rig, listed below in sig.

It depends on whether the game can use more then two threads, most games can't so far.
I don't know whether those games do or not.