How to find a used or donated computer

http://www.techsoup.org/mar/

What Is the Community MAR Americas Program?
The Community Microsoft Authorized Refurbisher (MAR) Americas program provides Microsoft operating system software to PC refurbishers in all the countries of North America, Central America, South America, and the Caribbean (with the exception of Cuba). The MAR Program is a partnership between Microsoft and TechSoup.

The Community MAR program authorizes eligible refurbishers to install the Windows operating system on refurbished computers for eligible recipients:

Windows 2000 Professional for all Community MAR computers supplied to eligible recipients.
Windows XP for computers with pre-existing Windows COAs. The pre-existing COA does not have to be for Windows XP. For example. a computer with a pre-existing Windows 2000 COA would qualify.
Microsoft Office 2003 Standard for computers supplied to eligible charitable organisations and other specially approved recipients, but not for eligible academic recipients.
The Community MAR program was created to increase the number of usable PCs available to nonprofits, schools, and low-income families across the globe by reducing the cost of software to refurbishers. The Community MAR program also benefits the environment by giving new life to a significant number of computers that may otherwise be destined for landfills.