which graphic card is better-intel graphic accelerator X3100 or GeForce 8500 GT

and will do the job with games like "far cry","rome:total war" and "call of duty 4"?

The 8500GT I believe, it is better but you should shoot for a 8600GT at the very least if yu want to game on medium-high settings.

The 8500gt is about 4 times more powerful than the GMA 3100.

It can also play all the games you listed (8500gt).

But even so they arent designed for gaming.