first off, if you dont plan on going crossfire/SLI, then a 500watt PSU is more than enough for that build.
and if you have the money I would get throw as much money in the GPU as you can! it really pays of in games!
I know memory is so cheap at the moment, but if I where you I would go for 8GB at a higher clock frequence.. something like 1866mhz. it probably wont have much effect, but niether will anything over 8gigs of RAM..
you can calculate the wattage you need here:http://www.thermaltake.outervision.com/
this might be my personal opinion but if I where in a tight budget I would just use the standard CPU cooler and get a better GPU. if you really want that cooler then the build look good.. :)