After a (rather busy) summer, I have finally elected to return to my "do it yourself network attached storage" project. I've done some reasearch, and picked my operating system -- FreeNAS (http://www.freenas.org). Their site describes it thusly: "FreeNAS is a free NAS (Network-Attached Storage) server, supporting: CIFS (samba), FTP, NFS, AFP, RSYNC, iSCSI protocols, S.M.A.R.T., local user authentication, Software RAID (0,1,5) with a Full WEB configuration interface."
There are a number of things I really like about this implementation. First, it's tiny -- and I mean really, really small. A full implementation takes about 30 megs for the operating system, leaving the rest of your disk space available for storage. Secondly, it's based on FreeBSD, so you know it's going to be rock solid, and require very little maintenance. Finally, in a heterogeneous network, this is ideal -- it talks to everybody. We have Macs, linux work stations, and windows all trying to play nicely together. This solution is perfect for our needs.
Give it a look. It's stable as a rock, and works like a charm.