Got through the day without too many problems. AbiWord seems to be the source of most of the problems at this point. I had to restart X a few times, but mostly avoided rebooting.
I picked up the sendmail book. It looks like it should be an easy implementation since I can just use NFS to export the spool to the workstations, making everything local. I'm not going to have the students emailing anyone other than each other and me for a while.
I have to start thinking about optimization--a customized kernel and figuring out which of the default daemons I can get rid of. In general, I have a bit less memory overhead (on my 32 mb systems) than I thought I would.