See also my firewall links for reference to IPCop and Smoothwall Linux firewalls.

• An example of the Linux filesystem (picture)
  • Shows typical subdirectories off the root of the Unix/Linux filesystem
     
• Linux tutorial/reference site
   
• Linux-iso.org (a resource for Linux iso images, such as Knoppix and Red Hat
  • Links to an insane amount of Linux distros (distributions) and links to find them. Quite a Linux site!
     
• Cygwin, a UNIX environment for Windows, for example you can get KDE to run inside Cygwin. Also, there's Cygwin/X which is a X Server and X Clients for Windows.
   
• OpenSwan, (an IPSec implementation for Linux)
   
• SAMBA reference site