I have a Dell Inspiron 545s with a 250w supply. Im currently running a 512mB DDR ATI Radeon HD4350. But I have started noticing serious flaws in its performance while gaming. I have a slim-line cabinet and require a good low profile GPU. I have short listed the HD 4770,HD 5670 and the nVidia 9800 GT. Which will allow me MAXIMUM GAMING POWER? (Im usually into racing games so i will require an unusually high frame rate.) Please help!