You do not need a different psu for the cpu. DFIs require more than 480W to operate stable. If you check out dfis forums at www.dfi-street.com they recommend the ocz powerstream 520W for the all around best power supply. As for the graphics card, the gtx really isnt worth the extra money because it only increases the fps by 10-15. Get the gt and save the money and buy something better now or later.
u should get a psu of at least 500w (higher is better) wid dat system ur tryin to build. i have an antec truepower 550w. very quiet and stable. works flawlessly powering up everything in my computer