Does the computer have a CD Drive? Can the CD drive boot?
Do you need JUST Linux, or a desktop too? You will never fit a good Desktop distribution on a floppy... but the base Kernel and Command Line Interface will run off a floppy.
You can get a disk/disc bootup utility that works like a bootloader on a floppy so you can boot off a CD, even if your BIOS dont support CD ROM Booting.