For those of you who need a firewall and have an old machine sitting around (like a Pentium 300Mhz with 8MB or more of RAM and a floppy drive), you need to take a look at Linux Embedded Appliance Firewall project. I have recently built a firewall on an old machine using the Bering Firewall. It loads from a floppy disk and only requires 8MB of RAM. It requires a little bit of computer knowledge, but it is worth the time investment.