Upgradeing my HP Pavilions Intel GMA X4500 graphics card?

Hi, i just got a HP Pavilion model p6277c with windows 7 its using a Intel GMA X4500 Graphics card, i play alot of online games like fallen earth,warhammer and so on and this card just isn't cuting it, can anyone give a idea of a good card that will work with this system am trying not to spend more then $150 or $200 doesn't need to be perfect but better was thinking maybe something in the 200 series GeForces