Some one thought it would be a good idea to try to install every version of Windows from 1.0 to Win7. It was interesting to see that what settings and programs survived the updates.
This was a little nuts, but the result is fascinating.
For example, a couple programs installed in Dos 5.0 still worked in Windows 7. The settings created in Windows 2 survived every upgrade until Win2k. The level of backwards compatibility MS supports is impressive.