Hi Vijay.
If you want to play games, get atleaset Sapphire HD 6570 1 GB. Costs 4480 on Flipkart.
More than 1 GB will never be used at your resolution. No use getting 2 GB card.
If you can't extend your budget go for Sapphire HD 6450 1 GB DDR3. Available at 2700 on Flipkart.
Hope this helps.