Ok, i've tried to zap the Pram, but it won't do anything. No beep saying that the pram values have been reset (other than the first beep when it turns on).

From that, it seems like it might be a problem with the PRAM battery. Tomorrow i'll probably look to get a new one to replace it, and also try to boot from a floppy that i've got lying around here. I managed to get some software for windows that lets me make a boot disk for my Mac, so I shouldn't have any problems if I write the floppy from my Toshiba Libretto.