What's your PSU ( power supply unit ) ?
You already have an inbuilt card ( 7025 ), but if you want to add a discrete GPU, then what's your budget ?
Also state the brand and model no. of the PSU that you have.
You will have to upgrade to a better power supply. Your budget is rs. 6000.. hm.
If you only want one graphics card without having the option to sli or crossfire(two of the same graphics cards) you should have around 550 watts. I would take a 600 watt power supply just in case.
Before I answer what graphics card would fit you best, please tell me what resolution you would play on, and how many monitors (if more than one). Thanks.
You should probably upgrade that PSU before buying a good card.
Spend a few bucks on a new one. How much are you willing to pay for a newer PSU ?
For Rs.6000, I'd recommend a HD 6670. Sorry, but there aren't much NVIDIA cards out there that can compete with it. Also, you wouldn't have to pay too much for the PSU, since it's the best performing card out there that doesn't need an external pci-e connector. http://cgi.ebay.in/XFX-ATI-Radeon-HD-6670-1GB-DDR3-HD-6...
It can do well at that resolutions and beyond, so you're good with it.