Software Suggestions 4 Donated Computers

From Microsoft's page regarding how to donate computers:

"If possible, keep the operating system intact. If you are donating
hardware with a pre-installed Microsoft operating system, keep in mind that
the license is only valid when used on the original OEM machine on which it
was first installed. Since charitable organizations usually cannot afford
to purchase and license new operating systems, a legal transfer (keeping
the machine and operating system together) can be very helpful. Linux and
Mac operating systems have different requirements, but we urge that
whenever possible, please pass on the operating system software with all
donated computers."

http://www.microsoft.com/education/TenTips.mspx

This page also has info on tools that "wipe" personal info off of the computer.

3/30 - Just heard from 2 large hospitals in Baltimore - they are incredibly frustrated by the fact they must protect the hospital and physically destroy all hard drives of old computers. Someone good at forensic reconstruction of a hard drive can bring back the information, so all HD's are put through a magnet, rendering them useless.

Anybody have solutions to this problem?