The option will appear on some bios programs while you're flashing. You should have room to put the old file on one floppy with your new bios file. Or use a usb drive. If the option isn't available, then check the board website for the old file and decide if you want to risk using the new file. Some manufacturer's remove old bios files so they are no longer available. You may have an unexpected problem with the new file, especially if you're overclocking. If you like your overclock, I wouldn't change the bios. Leave it alone.