Hi, I am considering buying a new computer, and the customization selection on the website where it is shown provides a selection of two different graphics cards. One is a GeForce GT 454, and the other is a AMD Radeon HD 6450 1GB DDR3, I don't know which one is better or if there is even a noticable difference. the computer that I am looking at is an inspiron 620, intel core. i5-2320, and 6GB of memory. Or should I buy a different computer altogether? Any help would be appreciated.