Low budget, use a 80486 or a pentium I with a linux on a floppy firewall, easy to install, secure enough and good performance. If you want to upgrade your network, no problem update your hardware or linux software and everything is running fine again... great performance for a low price (FREE !!!).

try bbiagent
You don't need to be a linux guru at all to get this to work. You only need a 80386 or better, 8 Mb Ram, 2 Network Interface Cards (linux compatible) and a xDSL modem. Configuration is made through your internet browser by typing the gateway/firewall local ip adress.

www.bbiagent.com
www.bbiagent.net