Help me decide on my video card.

Good day to all,

I need your help guys to decide which video card i'm gonna buy, and if you have any suggestion for a better card with the same price range?

these are the 660s

EVGA GTX660 SC 2GB DDR5
ZOTAC GTX660TI AMP! 2GB DDR5
Asus GTX660Ti OC 2gb Ddr5
MSI N660TI 2GB DDR5 Power Edition Overclocked
Asus GTX660-DC2-2GD5 2gb Gddr5

and the 7950s

PowerColor HD7950 3gb Ddr5
Asus HD7950 DCII Top 3gb Ddr5

P.S : is 500 watts of power supply enough with these video cards enlisted i have the FSP Aurum gold 80+ 500w or do i need to get a new one? i know in the forums benchmark the best would be the msi 660 do you recommend it also?

Thank you very much..