TARUN PV :
which is the best graphic card for intel core 2 duo 2.53 ghz processor
I'd agree with Quddro and say an HD 7770 will be good for your needs.
I'd highly recommend upgrading your CPU though- if possible. The Core 2 Duo is really out of date, and if you upgrade your CPU you will be able to use all the power of your graphics card.
What's your budget for your GPU?