I think i already answer on your 2 threads before...
It (500W Pro Series) should enough for your HD5770, don't worry about that...
I have got the Zebronics cabinet Dew. this cabinet has one side 80 mm fan and one back 80 mm fan.
Present I am having HD 3450 graphic card in crossfire. I am facing no heat problem.
Do I continue with the same cabinet or purchase a new one, when I install new MSI 5570 twin frozer with new 500 watt PSU.
I have selected this one: http://zebronics.net/Zeb_Bijli.asp