Need Help With Computer

Sup Guys,Birthday was July,19 didnt get anything big got the Razer Charcharias and a Graphics card i only get 60 to 91 FPS on Black Ops and MW2 On BattleField i get like 40 which sucks i was thinking of adding a New Graphics Card but i only have one slot for my Graphics i think so is there a way i can had a Graphics Card on my PC or how can i improve my FPS i might Just go with a Razer Keyboard. mmmm...I have a Geforce GT440 1GB DDR3 Runing Black Ops on High and MW2 On High Setting well Extra On Crossfire i get 260 i believe but i dont have a good Processor Intel(R) Core(TM) i3 CPU 530 @ 2.93GHz (4 CPUs), ~2.9GHz think i should just get a new Processor for more FPS Budget about 100 Dollars Hope i can get help.

PS:http://reviews.cnet.com/desktops/gateway-dx4831-01e/4505-3118_7-33964710.html thats my pc