Graphic card help needed?

I am looking for a graphic card for my PC.

My PC has following config:

AMD FX4100 Quad Core 3.6 Ghz

4 GB DDR3 RAM (may upgrade to +4 GB)

1 Tb + 80 GB HDD

22" LED display (1600 X 1200)

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I want a graphic card less than $100 (In India)

So I saw these :-

A: ZOTAC NVIDIA GeForce GT 630 Synergy Edition 4 GB DDR3

(810 MHz GPU Clock Speed, PCI-E 2.0 x16 Bus Standard, 4 GB DDR3, 3D Vision Support, 2560 x 1600 Maximum Digital Resolution, 300 W Power Supply Required)

and

B: Sapphire AMD/ATI Radeon HD 6670 1 GB DDR3 Graphics Card

(800 MHz GPU Clock Speed, PCI-E 2.1 Bus Standard, Shader Version 5.0, 1 GB DDR3 Memory, AMD 3D Vision Support, 2560 x 1600 Maximum Digital Resolution)

I never had a graphic card, so I don't know much about them.

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I am not a hard core gamer, just casual to pass out hot Indian summer.

Also I can put my PC right infront of Air conditioner, so it won't get ever much hot.