I'm trying to help my friend fix his Dell OptiPlex GX400, which is running Windows XP Home, and is probably owned. It only has 128 MB of RAM, and it turns out this particular model uses expensive 128MB PC-800 Rambus RIMM for Dell RAM Memory. So, it doesn't make sense to buy a chip, really, and none of my spares will probably fit.
Instead of throwing hardware at the problem, I looked at Damn Small Linux (DSL information) To burn a CD of Damn Small Linux, Download the ISO and then burin it to a CD, in Windows, with InfraRecorder (GPL).
DSL is based on Knoppix, but is stripped down to a bare bones set of Debian packages. As promised, booting DS from the CD transformed the slow, almost unusable computer into a speed demon. Plus, DSL shows system resource use right on the desktop, and we could see that it was hardly using any RAM -- less than 20% of 128 MB.
Now all we have to do is figure out a way to save the configuration, and configure networking.