after your post spigen i just gave you a whole explanation about the psu situation and the ram. but anyway settle for an 620hx/520 or one of the psu's verny mentioned.
DDR3 is a waste, I saw you said 4 gigs for only 300 bucks??? My ram is slwoer (800mhz which is still fast), and on Tiger they are 25 bucks for 1 gig dual channell. get 4 of those and u can handle anything at a third of the price.
mhz is not everything, 1066 kits have higher timings which you would have to tighten to improve speed which would limit how much you could overclock your ram.