crowe is correct, you will not see any difference between the two ATI 5770 you listed. get the cheaper one. you can Over Clock the ATI 5770 anyways, it runs very cool.
as for your PSU, its not great. I know the better brand names are very expensive in your market (more so then in north america). your PSU will be OK as a stop gap but look for an OCZ, xigmatek, CWT, etc.,. brands that are not as well know but have decent quality.