You can use the Nvidia Nvflash utility version 5.06 to flash your video card BIOS. You can only use this tool in DOS mode, this means you have to boot from a MS-DOS boot floppy:
To backup your BIOS: A:\>nvflash -b a:\backupbios.bin To flash your BIOS: A:\>nvflash -f a:\biosnamehere.bin
This tool is only recommended if you are 100% sure of what you are doing. Tampering with your BIOS can be a very dangerous thing.