If you can;t read the disks - you might need to get a Mac and a floppy drive - 1.4mb isnt too hard, you could probably get a USB floppy to read those; when you are talking about 800k or 400k disks you will have to look for an older mac to read the disks as the drive mechs/logic are a bit different.
If the computer is that old getting data transferred would probably be easiest with a modem-modem connection, or a null-modem cable.