Well, I got the netbooting thing working pretty well. In the end it was a 128MB box because I have no idea what NIC the 16MB boxes have.
The startup sequence goes something like this:
- GRUB boot up (as below)
- /sbin/init is a shell script
- Connects an NBD (see linux-src/Documentation/nbd.txt), mke2fs's it and mounts as /tmp
- mounts proc and so on
- Prompts for a username and smbmounts their home directory (symlinking /tmp/home to it)
- Starts X and Mozilla
Which, all in all, is pretty sweet. I need allow anonymous logins and error check some more stuff in that script. I also need to setup home dirs with good Mozilla defaults (proxys setup etc). But nearly there.