ATI Radeon HD 4300/4500 Series
Thats rather weak card from ATI radeon
In my opinion overclocking GPU may help
Also buying a new card might be a solution but if you don't have any money then overclocking should give you few extra FPS if done correctly with AMD catalyst .
Btw i don't understand . Do you have 2 cards in crossfire ? Or you don't know which series you have ?