i do not know a lot about raidmax psu's but i think you would be better off with a corsair or seasonic psu cheaping out on a psu is not a good long run decision
Well it depends on what you think looks cool when it comes to the case. I would suggest doing a little more case research on your own to figure out what you like. If you like lights and windows, or if you would rather have a minimalist approach, I can try to find you something.
Here's what I would do with $800 though:
http://pcpartpicker.com/p/qZ13
Other things to think about upgrading down the road are adding an SSD and CPU cooler.
There's no real difference between the two cards. One might be overclocked higher than another, and one might have a better warranty, but that's about it. The coolers are probably a little different too. Other than that, they're pretty much the same card.
Also, here is an AMD alternative with an SSD and CPU cooler for $800: