Definitely go for a 4GB version of the 960 and don't listen to the people who say it doesn't have enough bandwidth blah, blah, blah... Anyway, the MSI GTX 960 Gaming 4G is pretty much the best 960 you can get, so that is what I would recommend.
Also, I'd get the 550 Watt version of the power supply just to give yourself some headroom.