Of course, if you want good performance for a business network you'll need more power than that, but I've got a client with 11 workstations running it fine on a Core 2 Duo CPU and 4 GB RAM with a 25 Mpbs Internet feed. It'll work on 1 GB of RAM, and takes about 200 MB of HDD - the 2 GB HDD I'm running it on is almost empty. I have it running on my home network on an old AMD Sempron CPU. It uses almost anything in the way of hardware. Smoothwall Express (SWE) is great for what it is intended to be: Free Linux-based dedicated firewall protection for the small business network.