Apoorv Srivastava :
I know my components are weak, that is why i am upgrading in the first place.
and dont worry, no offence taken. I am from India and my budget would be ideally under 200$
Thank you very much for your response.
Upgrading either your CPU or GPU now, you could upgrade again in the future and be up to date with modern "technology". However upgrading only your CPU or GPU will not allow you to play FIFA 15. Personally I would upgrade both your processor and graphics card; I would do this by purchasing used components from eBay, that way you can upgrade your system to adequately play FIFA 15.
Keep all your current components, including your motherboard and just replace the CPU and the graphics card. Your budget, 200 United States Dollars (USD) equals to around 12,210 Indian Rupees (INR). So upgrade your Intel Core 2 Duo to a Core 2 Quad, and replace your GPU to a Nvidia GeForce GTX 560 Ti; I would recommend better components, but they are the best I found within your budget (I didn't find many products on eBay India either).
CPU: Intel Core 2 Quad Q8400 2.66GHz Processor (Rs. 2,500 @ eBay)
Video Card: Forsa GeForce GTX 560 Ti 1GB Video Card (Rs. 6,999 @ eBay)
Total: Rs. 9,499.00
Both the CPU and GPU are compatible with your existing motherboard, tied in with your 8GB RAM, you should be able to run FIFA 15 more than at a satisfactory frame rate.
All the best.