Hey, I want to buy the HPE-270f and upgrade to a GTX 460 SLI build. Will they fit, and what is a good power supply to upgrade to for this build? HPE-270f: http://www.shopping.hp.com/webapp/product/BK175AA%23ABA GTX 460: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130566 Thank you.