What would happen if I modified fstab so that my / partition on /hda1 is mounted as read only? Would anything run? I need to set up a system that can not be permanently modified or damaged by public users.

There are several distributions that run from cd (knoppix comes to mind) so I have to think it is possible. Would the chroot capability not do what you need?

/tmp and /var both need to be writable, but otherwise, it would work. You could make ramdrives for everything you need to be able to write to.

Thank you both! I thought about chroot, but wouldn't it be very difficult to add all of the hundreds of little binaries that make up XF86 to the chrooted environment? If not, please let me know- I wouldn't know where to start. As for the read-only method, can I modify fstab as mentioned and then put /tmp and /var on separate read-write partitions to make the system run?

Yes, all you have to do is modify fstab. If you want, you can even use only one RW partition. For example, make it /var, and make /tmp link to /var/tmp. As long as /tmp is mode 777, it will work.