Anthony collects old computers and donates them to people who can't afford to buy new PCs. But he has some really old ones that can only really run Windows XP. The problem isn't Windows, per se, but the browsers. Leo says yes, browser developers aren't updating their support for XP. So people can't get online with old browsers anymore.
So what can he do with them? Leo says that hardware that can no longer support modern windows are ideal candidates for Linux. Leo says that Puppy Linux, Damn Small Linux, and XUbuntu are versions that are designed for old hardware. And since Anthony has no budget to support his project, Linux becomes very attractive, since it's open-source.
By making a Linux setup customized to be easier to use, Anthony can provide them a viable option for those who can't afford a more modern system.
Another option is to put ChromeOS on them and turn them into defacto Chromebooks. It'll depend on the hardware, but it's doable. Check out NeverWare's CloudReady. That option is really good for kids who need a computer for school. Most schools use Chromebooks these days, making them not only ideal but locked down.