Best upgrade for my machine?

[officialgmania]

Hello,so this is my current machine

Motherboard:Gigabyte GA-M68MT-S2P
CPU:AMD Phenom II X4 955 BE 3.2 GHz Processor
GPU:Nvidia Asus GTX550TI 1GB DDR5
RAM: 8GB 1333MHZ
CPU Cooler: Stock AMD Fan

so im thinking off getting a Hyper 212 cooler,to overclock my CPU a bit and so its quieter,anyways what graphics card could you suggest thats quite cheap from 0-£150 max?#

thanks!

 

[renz496]

7850?