You can make an lrp (linux router project) box, and you need only a pentium or a 486 with 2 network cards. An lrp box is very stable, you have total control, ...., you mustn't shut it down. You can make the comparison with a profesional cisco router.

More info:

- http://leaf.sourceforge.net

- http://www.pigtail.net/LRP/ (very good + I use it)

Maybe I will write a tutorial on this, but I think the site here above is a very good tutorial. You must only do four things: 1) collect the necessary hardware (2 NIC’s + Pentium)
2) make your floppy disk with the lrp os on it + the modules for your NIC’s
3) boot up, configure your dhcp server (change the dns name’s)
4) Configure the clients: - check Obtain DNS automatically
- open a command box and type ipconfig /renew

That’s all, very easy. More detailed information you can find at pigtail.net/LRP
And you have many options (comparison Cisco router: http://www.pigtail.net/LRP/linksys.html) + many more