Yeah, it should work fine, as long as youre not already using up all of the PCIe slots on your mobo. And if I'm familiar with your motherboard, it has 2 PCIe slots, so I guess you could crossfire it with another 6670...
On the topic of other graphics cards for 5000 rupees, I'm not sure how much that is in USD but the radeon 6770 is never too much more than the 6670. The 7770 should be in the same price range as well.