The firewall project IPCOP has finally released v1.4.0 of this great Firewall. I have been running IPCOP for about 2 years now and I can truly say that this is a very good firewall that will run on most of your old hardware, I am running mine on a P133 with 64MB RAM but some people are even running it on 486 machines!
New in this version is support for SCSI disks and SMP so now my old dual P200mhz Proliant server has a new task at hand. For a full changelog go to the official IPCOP site for addons go here and for support forum go to IPCOPS.net