CamCam107 :
Are you sure the stock fan will be fine?
if youre not going to overclock your cpu, yes, its better to invest on the gpu first, my suggested one is a big jump from the one you picked, just get a cheaper paste from cooler master or deepcool, im currently using the Deep Cool Z5, works great man, my 955BE idles at 34C and 55C during gaming @3.6gz.