I built new computer and i am wondering why it lags on high settings and ultra?

You would probably be right, that's not a great video card. I use the same one on my single core machine and wouldn't consider something like that on a quad core. It would bottleneck it. I really love the 6850 Overclocked card I have listed in my sources, if you're willing to shell out $170, it's benchmarked pretty high. I am also including a link to a site that shows that the 5670 almost doubles the 4670 in fps on Halo on max setting, and X3 goes from just over 10 fps on the 4670 to almost 50 fps on the 5670 on max setting, just to see how big the generation gap is.