Which is the new graphics card that you bought over 9800GT? If it's HD5770 then it should run better.
And fps is frames per second so no need to say "
20 fps per second".
Anyways i think the old Nvidia drivers might be causing trouble.
Uninstall your graphics driver and then use Driver sweeper to clean all Nvidia and ATI chunks & then restart and install the drivers again then restart again after the installation is complete and see if it fixes the problem.
Moreover i suggest you install the latest ATI drivers from the web not the one that came in the Disk with your G.card.