Thanks for the reply guys
the thing with 4770 is the availability issue my friend and 4850 is indisputably better though i agree it consumes less power.If it was the hd4750 its a different ball game as it is rumoured to be much cheaper and almost as powerful as 4850.
at the end of the day it boils down to power
and 4850 provides it with the best price/performance ratio