Upgrading ATI Radeon HD 5570, $90 budget

[hbenitez2000]

I pre-ordered Watch_Dogs and I know that I have to upgrade my graphics card. I'm new to graphics cards so I have no idea what to buy, I want to play the game on at least 60fps on medium settings. I'm not planning to overclock it or do SLI/CrossFire. My monitor resolution is 1366x768.
PC specs:
CPU - Intel Core i5-3330
Mobo - GIGABYTE H61M-S2P
RAM - 6GB (4gb and 2gb combined)
GPU - ATI Radeon HD 5570 1GB
PSU - Cooler Master Extreme Power Plus 460W
Case - I have no idea what the model is but it's a Trendsonic case
Monitor - AOC e1620Swb 15.6" (I know, it's small)

I am from the Philippines (Cebu), I can buy graphics cards in a lot of shops in the mall. I'm considering a GT 640 1GB, what do you think about it?

 

[unksol]

not about the graphics card but your PSU is absolutely terrifying. I wouldnt use that thing in any PC

 

[hbenitez2000]

not about the graphics card but your PSU is absolutely terrifying. I wouldnt use that thing in any PC

I know, I'm planning to replace it soon