Re: My computer build
Well the 295 is a dual GPU card, while the 285 is single. As for the performance difference, its probably negligible for gaming. You would notice a difference in benching for sure, but the 285 is very powerful.
How soon are you ordering as well? ATI's 5000 series cards are due out in two or so weeks, which are Dx11 and there should be something similar to the 285's price.