Need help upgrading hd 5670

What sites can you buy from?

flipkart.com

some cards from flipkart:
HIS AMD/ATI Radeon HD 6850 GPU 1 GB GDDR5 Graphics Card Price: Rs. 10640
http://www.flipkart.com/computers/components/graphics-c...
HIS AMD/ATI Radeon HD 6790 GPU 1 GB GDDR5 Graphics Card Price: Rs. 9296 (currently out of stock)
http://www.flipkart.com/computers/components/graphics-c...
HIS AMD/ATI Radeon HD 6770 1 GB GDDR5 Graphics Card Price:
Rs. 8008
http://www.flipkart.com/computers/components/graphics-c...
EVGA GeForce GTX 560 Superclocked Price: Rs. 12826
http://www.flipkart.com/computers/components/graphics-c...
Sapphire AMD/ATI Radeon HD 6850 1 GB GDDR5 Rs. 10943
http://www.flipkart.com/computers/components/graphics-c...
from another website (if they deliver at your location):
MSI Radeon HD6790 1GB DDR5 ATI PCI E Graphic Cards (R6790-2PM2D1GD5) price: rs 9020
http://www.theitdepot.com/details-MSI+Radeon+HD6790+1GB...(R6790-2PM2D1GD5)_C45P13239.html
HIS Radeon HD6790 Fan 1GB GDDR5 ATI PCI E Graphic Card (H679F1GD) price: rs 8840
http://www.theitdepot.com/details-HIS+Radeon+HD6790+Fan...(H679F1GD)_C45P12588.html
HIS Radeon HD6770 Fan 1GB GDDR5 ATI PCI E Graphic Card (H677FN1GD) price: rs 7580
http://www.theitdepot.com/details-HIS+Radeon+HD6770+Fan...(H677FN1GD)_C45P12589.html
XFX Radeon HD6790 1GB DDR5 ATI PCI E Graphic Cards (HD-679X-ZRFC) price: rs 9665
http://www.theitdepot.com/details-XFX+Radeon+HD6790+1GB...(HD-679X-ZRFC)_C45P11917.html
HIS Radeon HD6850 Fan 1GB GDDR5 ATI PCI E Graphic Card (H685F1GD) price: rs 10105
http://www.theitdepot.com/details-HIS+Radeon+HD6850+Fan...(H685F1GD)_C45P12587.html
Msi Radeon HD6850 1024MB GDDR5 ATI PCI E Graphic Cards (R6850 CYCLONE 1GD5-PE-OC) price: rs 10115
Asus Radeon HD6850 1GB DDR5 ATI PCI E Graphic Cards (EAH6850-DC-2DIS-1GD5) price: rs 10450
http://www.theitdepot.com/details-Asus+Radeon+HD6850+1G...(EAH6850-DC-2DIS-1GD5)_C45P9388.html
among these, the geforce gtx 560 is the most powerful followed by the 6850.
in terms of power (from more powerful to less): geforce gtx 560 > radeon hd 6850 > radeon hd 6790 > radeon hd 6770. imo 6850 offers good price, performance and power efficiency.
recommendations are based on price. look up the review of your chosen card. make sure that your chosen card fits with the rest of your pc.

What about gtx 465?

what about it? a geforce gtx 460 1gb is better than a 465. and the gtx 460 trades blows with radeon hd 6850. 6850 is the newest of these three.
if you must get nvidia features like physx, 3d and want to overclock the gfx card, get a gtx 460 1 gb instead of a gtx 465. get the 256 bit memory bus and 1 gb gddr5 version, not the 192 bit version or 768 mb vram one. gtx 460 is older gen. (still a very good card).

I am thinking of palit gtx 460 sonic platinum it is factory overclocked and it looks good to me. How about it?

yes the gtx 460 is good but with that budget of rs9000 go on local hardware shop in your city and get a hd 6870.buying from online shop will cost you more because i am also from india in mumbai i am buying my pc components from hardware shop.if u wanna buy an graphic card then only buy from flipkart it is a well known online shop but you should from a hardware shop if u want to save money because in india most of the are buying pc components from hardware shop thats why there will be low price belive me. 

you'll find the palit card's info in this roundup:
http://www.tomshardware.com/reviews/geforce-gtx-460-rou...
review:
http://www.techpowerup.com/reviews/Palit/GeForce_GTX_46...