Sometimes in wandering the Interwebz, I encounter things I just need to share. This week, I encountered a video where a man with WAY too much time on his hands decided to create a virtual machine in VMWare and try to install every version of Microsoft Windows, in order, straight through and see what happened.
He started with an installation of MS-DOS 5.0, which was required for most of the early Windows installations to work. He then installed Windows 1.0 over top, since Windows was merely a GUI shell until Windows 2000. From there, it was upgrade after upgrade; never a clean installation.
At Windows 2.0 he set a desktop and titlebar color scheme that was definitely unique, and that scheme was carried through right up until Windows XP. In Windows 3.0, he created a program group from some DOS applications he had installed, like Monkey Island and Doom II, which were surprisingly carried through the modern Windows 7. That's over 25 years of software compatibility. You can't say that for all computers.
If you're a big Windows fan and have 10 minutes to watch the process, hit the break and see the compatibility wonderment.