Free Geek is a non-profit organization that accepts old computer equipment, rebuilds it -- as needed -- with a Linux-based system, and then sells or donates the equipment to needy schools and non-profits.
If you don't need a computer, you should still check out these guys as a place to donate equipment cost to. There are some expenses involved, but wouldn't you rather have your equipment going to worthy new homes rather than to a rural community in China already poisoned by the toxic debris of melted down circuit boards?
In case you were wondering, these old computers will function pretty well using Linux. Linux does not have the same hardware demands as Windows. Plus, you can always use these units as terminal server clients.