How plentiful Ghz on a Duo core and a Duo Core 2 would be pious for games?

Games approaching GTA, True Crimes (free roaming ones)

How plentiful Ghz on a Duo core and a Duo Core 2 would be pious for games?

I have the 1.66ghz core duo, and it runs everything I ask it to. It handle BF2 easily, and FSX, which is a massive program.

Ive built slightly a few core 2 duo rigs, from 2-2.6ghz, and they are all incredibly powerful, and when combined with a sata 2 firm drive, they fly.

The any of the core 2 duo's will do, trust me.

You should concentrate more on your video card, And it would be alot smarted to go next to a moe expensive video card over going with a 2.6ghz or high Core 2 duo.

The 6600gt and X1600 are the lowest cards you should go next to, I have both, and also hold a 8500gt and 8600gt, and recommend both, particularly the 8600gt, which score about 10,000 within 3dmark, the same as the 7950gt.
I can not narrate on a Duo Core, simply because I don't even mess with them. However any Core 2 Duo would be enough for both of those games. HOWEVER you must also consider your video card and memory. Those are 2 more primary factors contained by running games on computers.
The most important item is your graphic card... I'm sure that any Core Duo would work fine... they are extremely promptly.