There's a lot of possible devices out there - network cards, video cards, SCSI controllers, IDE controllers, monitors, and so on, all with different interfaces and such. I doubt you could encode information about every device under the sun on one floppy.

Here's my idea: On the disk, have a modular kernel of some kind, and drivers (or just parameters, with instructions on how to build drivers) for every network card and modem in common use, and PPP/TCP drivers. The machine creates/loads a driver for its network card, connects to the internet, and downloads information/drivers for everything else in the system, and goes from there.

Of course, that sounds like your average Red Hat/Debian network install, but who cares?