Closer! I removed 3/4 of the RAM, so its down to 512mb. On the third disk, it gets to "Loading, please wait...", it beeps, the CD drive spins up and the access light flashes a few times... and then the system halts with "System Installation failed to start the session."
Yes, set copyfromfloppy=1 is in the config.sys so that the drivers are loaded from the floppy diskettes rather than the installation CD.