I'm afraid even at those lower resolutions, your CPU does not meet minimum system requirements.
So if you want to play watch dogs, you will need to change at least CPU and GPU.
I sincerely do not see how you could do that for less than 200 USD...
However, in that resolution, maybe you could play with an i5 2400 or similar and a 7770 or similar.
I guess this is the cheapest you could make, but you have to check your motherboard and PSU can support those...