i am on very low budget here.since the dollar hike in my country.
so, will this 7750(subject to my current budget) work with DC7800 core 2 duo without any difficulty.
and also which high end games can work with 630 1gb or 6670 2gb.
yes a 7750 will work with your cpu, the real question is the wattage of your PSU. 6670 w/2GB is a marketing ploy, a 6670 can never make use of 2gb vram. A 7750 would be the best bang for the buck out of any of the gpu's you listed and would prolly last you longer gaming-wise too.