12. Convert it into a test machine
If you regularly fall foul of viruses and the like, consider pressing your old PC into service as a test machine. You could even use it specifically for opening attachments or downloading programs from the internet, thereby creating another layer of security and removing your main PC from the front line. It's also worth using your test machine for installing software, whether you want to compare a number of programs without cluttering up your main machine or you need to make sure a program won't cause any problems.
13. Play classic games
Classic PC games from the 1980s and early 1990s don't always run on Windows XP because they're designed for the archaic text-only DOS operating system. So have that old PC dedicated to running DOS. If you have the original install floppy discs or can find them on eBay, great; otherwise give FreeDOS a try. You'll find that most old videogaming systems can now be emulated by special software.
MAME is the most widely used and recreates old arcade machines and their games. Download the latest version of MAMEUI, connect up a USB gamepad and, if your CPU can muster 100MHz or above, you're away. You'll need to supply your own game ROMs – a number of legitimate ROMs can be found at www.mamedev.org/roms. Other ROMs on the internet haven't been cleared for use, so they're illegal. If you're really keen, you could even buy a classic arcade machine (for around £200 on eBay) and then fit your old PC into it.
14. Use it as a backup device
Rather than ending up with an ever-growing, 20ft pile of CD-Rs, simply copy all of your important files from your main PC to your old one regularly – a £10 USB flash drive will do the job nicely. Alternatively, if your PCs are on the same network, you can use the free version of SyncBack from www.2brightsparks.com (click Downloads > Freeware) to back up your files automatically every day.
15. Turn it into a firewall
Even the dustiest old 486 can be used as a hardware firewall, standing as a permanent barrier between the internet and your main computer to prevent any undesired information requests from reaching your important data in the first place.
Give m0n0wall a try. Setup is too lengthy to explain in just a few words, so follow the helpful guides on the site to get it up and running. There are a few things you'll need to know about your internet connection, such as which category it falls into. Most broadband ISPs in the UK use either static IP or PPPoE.
This is the kind of information you'll usually find on your ISP's website, but if you have no luck there you'll have to contact them directly. M0n0wall's system requirements aren't excessive: it requires a minimum of 64MB RAM, a Pentium-class processor (you can get away with a 486 CPU if your internet connection is less than 10Mbps) and minimal hard drive space; in fact, the firewall can be run directly from a bootable CD/floppy drive (the latter is used to store your settings).
