Don't throw away those old PCs yet. Whether you're cleaning out or upgrading the computers in the office or at home, you should be able to find something to do with them.
As we'll discuss, you can use them for experimentation, routing, security, file or Internet serving, and more. Make one of the projects your late-night endeavor on the weekend or your new project at work.
#1 Install Ubuntu or other distribution to experiment with Linux
If you haven't already, you could discover the world of free and open source computing by fiddling around with Linux. Within an hour or so, you can download and install Ubuntu, or one of the other thousands of distributions (distros) onto your old PC. You can even test it out before installing anything to your hard drive, using the live CD mode of some distros.
Ubuntu has become very popular, especially for Linux newbies. "Ubuntu" is an ancient African word, meaning "humanity to others", hence their philosophy and mission to better the computing world. You can read more about this distro and download Ubuntu from its site. You might also want to check out a previous article of mine on this site: Discovering Ubuntu as a Windows User. To discover other distributions, check out DistroWatch.com.
Once you boot into a desktop version of Linux, you'll see that though it looks different from Windows it still has the same main features. There's still a start menu--usually better organized than in Windows--and icons on the desktop. Average users should be fine typing up documents, browsing the Web, and doing other basic tasks.
The biggest advantage is that you'll now have access to hundreds of thousands of totally free applications. Some are small projects, however some rival that of their commercial counterpart, such as OpenOffice.org and Microsoft Office. Most distros are actually loaded with all the day-to-day software you'll need: an office suite, email client and calendar, Web browser, photo editor, and more.
For additional applications, you can use the Package Manager to search for and install other software that's listed in the distro's repositories; or download programs directly from a developer's site and build them manually.
Linux is actually the operating system for many computer and networking devices. The rest of the ideas in this article also use Linux-based software.
#2 Make it a router with RouterOS or ZeroShell
Advanced networking features, such as found in Cisco equipment, can be at your fingertips with little or no cost. Linux-based operating systems can convert your old PC into a multi-purpose LAN server. Use it to replace your off-the-shelf router by running the firewall for your network and sharing the Internet access (with NAT). You might even connect your offices together using the VPN server and client, offer public access by configuring the captive portal, or use balancing and fail-over for redundancy. The features and solutions are essentially endless.
Two popular projects you should look into are RouterOS and ZeroShell. ZeroShell is free and can be ran from the CD with the configuration saved to a hard or flash drive. After minimal configuration at the console, you can administer it via a Web browser on a remote computer. RouterOS has been around longer and is more established. It installs directly onto a drive and has multiple configuration interfaces, including Web-based and a custom GUI application.
For help with ZeroShell, check out my tutorial series on one of our sister sites, LinuxPlanet.