The GeForce2 series is an old generation of graphics cards, and Fiesta puts more stress on it than it is capable of handling. I suggest installing the StarStorm drivers.
These drivers have been tweaked and modified by a third party to perform better and with better image quality.
NVIDIA StarStorm 56.72 X Drivers
I suggest you to have a back up of your original drivers at the ready, in case this driver proves to be no good.
Another thing you could do to relieve stress on your card is by playing Fiesta in a window at 800x600. However, it looks like you're currently doing this.
If neither of these work, then your only real option is to upgrade your graphics card.
Threaded Mode