Often times when setting up a test lab, I will use a Linux system as a router/firewall. While this works, it requires somewhat intimate knowledge of Linux setup and networking – something not everyone is going to have. I found the Vyatta platform is a nice hybrid between a Linux server and a network appliance. It allows for routing, firewalling, DHCP/DNS, VPN, and more.
The easiest method to get started is to download the latest OVF file from http://www.vyatta.com/downloads/vmware_ovf.php