Nixadmins.net

Many small companies out there struggle with firewalls and viruses. This is a great guide to set up a free firewall between the so dangerous internet and your local resources.
It’s a cheap and effective way to protect your network and the howto is easy to follow even for someone who hasn’t used *nix a lot.
Quote from HOWTOforge:

Scope: creating a firewall/(mail)gateway for a small network (say 10 to 15 users or so on a PIII 450MHz, 512 MB ram and two identical network interface cards, broadband connection, fully featured, for a bussines environment. Better specs of your hardware (notably the amount of ram) will improve the performance of your server significantly. The specs mentioned ar a bare minimum for not so demanding customers, yust to indicate that if you really want, it can be done indeed (need to do some tweaking afterwards though).

For anyone who wants to know the differenses between theese two operating systems I suggest you read this great comparison from Widefox wiki.

This aims to be the most comprehensive kernel comparison of the latest most popular Unix style kernel verses the latest most popular current kernel. A kind of kernel comparison FAQ.
In Q4 2006, this means Linux 2.6.18, 2.6.19 kernel verses Windows Server 2003 R2 kernel.
In Q1 2007, this means Linux 2.6.20 kernel verses Windows Vista kernel. Johnathon Weare