HI i am new so be kind haha dont know much about computer really well my question is i have a hp 6045uk specs http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01729476&cc=uk&dlc=en&lc=en&product=3929066 and my graphics card is a geforce 9800 1g just wonderd what other graphics cards are better that i can run on this computer and which i will see a diffrence with and with out changing power supply cheers