ones 512 meg the others a gig
Can you no afford a 5670 instead? so you get DX11
There is the 600 watt modxstream
http://www.ebuyer.com/product/174182 couple of people do not like em but ive used loads and none have blew on me running one now in main machine and one in second machine both over a year old
DDR3s price is dropping on some sites ive seen Kingston down below £60 for 4 gig
I also think you are scimping a bit on the screen really to do justice you need a proper HD screen 22" +