Run it on the stock hsf for now, when you get another 30 bucks slap a hyper 212 on it, unlock it to a quad and overclock. That will be FAR more performance than you could EVER see out of the dual core. Athlon II. So thisvway your CPU isnyva complete throwaway part
The 4850 shouldn't be horrible with your res and I cant really come up with better in the budget.
If you aren't buying for 3 months though this discussion is silly. that 4850 will be gone, prices will change, parts will be discontinued. I dont see that you have a PSU? and save up another 50 bucks for a modern GPU