Last year someone threw out an old Toshiba Techra laptop that was still in working order. It was a very old machine as it had a 37 Gb hard drive 256 megs of memory, one USB port and no wireless networking. I checked out the machine and could not see any personal information on it. If there was anything there I would have wiped the files. For a while I used that laptop as an emergency machine, or, if one of Emily's friends visiting needed a machine it was there for them. This machine was running XP and it ran very slowly, but, it ran. Since XP is not being supported I wanted something running on the machine that is a bit more secure, but, light on what it needed for hardware. I found a lot of candidates when I searched DistroWatch and did a search. I found one called Netbook that appeared to fit the bill and I downloaded a copy and burned it to a CD. I had to burn a CD as the Toshiba machine would not boot from the USB stick.
I rebooted the laptop with Netbook and it didn't take very long to launch and bring up a working system. I clicked on the network and it auto detected the USB network card and it was working! It was moderately responsive running from the CD and I figured it was safe to install. I followed the steps and I thought I had a working system. I did a restart, but, the machine wouldn't boot. I went back and read that I had to set GRUB and once I followed the menu options from the Netbook CD I had a working machine. The next reboot worked and I was up and running. The basic system is working and we now have a spare machine that can connect to our network. Firefox runs well and takes maybe 5 seconds to launch on the machine. I will be dropping off the machine in our daughters office that we set up in the basement for her and she has a nice low end machine for her friends to use when they visit and don't have a laptop.
If you have an old low-end machine that still works I would recommend checking out what DistroWatch has available for Linux distributions and try them out on CD/USB on the machine. You can then get a bit more life out of the machine and have a secure system running. The only downside is that Java isn't installed by default and I haven't tried to do an install for Java, but, there is only one site (Runescape) that I was interested in testing it on and I know the system wouldn't be able to run it at an acceptable frame rate.