I would like to upgrade my graphics card and power supply. I was eyeing the new Asus - ATI Radeon HD 4890 and im not sure if it is compatible with my computer (HP e9220F). Or if it would even be worth installing in this particulor computer, ie; will i be able to use it to its full potential? If so, what power supply would i want to buy? If not that graphics card, what would you recommend?