My pfSense router is built out of an old HP 6000 Pro machine, it is configured as follows:

• Pentium E6300 2.8Ghz (dual core)
• 2GB RAM
• 160GB HD
• Onboard Intel Gigabit and 4 port Intel PCIe Gigabit NICs
  1. WAN Interface – CenturyLink 140/20mbps vDSL2
  2. LAN Interface – 192.168.1.0/24
  3. IoT Interface – 172.16.0.0/16 (internet only)
  4. CCTV Interface – 10.0.0.0/16 (no internet, only access to NVR)
• Traffic shaping (20/1mbps cap on IoT)
• QOS priority on VoIP

Normally for a router I would have used a small 4-16gb solid state DOM or CF card for the OS, however in this case I am also running squid caching proxy, so I decided to use a hard drive for a bit more cache capacity and the extra write cycles it will need, eventually I will swap in an SSD.