Need Help : Graphics Hard

Graphics card suggestion

Hi,
I'm Having a Desktop
Intel i5 processor 3.20
DH55TC
4 GB DDR3
Intel HD Graphics
I need to upgrade my graphics card
Purpose of graphics card is online games like uberstike and Converting High Definitions Videos
i have plan to buy Nvidia Geforce GT-520 1GB DDR3 PCI - RATE : 2800 rupees.
Budget is 3500 rupees
Any other suggestions ...