If you have a machine with a 266mhz or better processor, 64mb of RAM and two network cards, you're already in business. Essentially, IPCop is an entire Linux distribution custom tailored to being an incredibly powerful firewall and router. I've setup many - at my house (FiOS), my inlaw's house (comcast), friend's house (DSL) and my colo (switch handoff to their upstream providers). Once you step through the 5 minute installer, it reboots and you have a functional firewall/router. It's got a nice web based admin tool, so no need to much around with the OS itself (unless you want to).