Microsoft Windows Through the Ages

"I got the idea from a 90s computer magazine article I vaguely remember (possibly from PC Format?), which essentially did the same procedure but only from Windows 3.0 to Windows 98. Since virtual machine technology is much more mature now, and there are four additional versions of windows, I thought it would be a great time to repeat the experiment. I installed Doom 2 and Monkey Island as tester applications, as I found the installation disks for them while I was looking for Windows disks, and those were two of my favourite games from the period (and still are)."

I have to say that I am really impressed with the work done by Andy and Microsoft.  A project like this, testing the upgrade facility within Windows, is rather large and needs meticulous attention.  While I doubt that there is any computer in the real world that has gone through this process, watching the video feeds the geek in me.

I also find it amazing that the whole process worked and have to give credit to Microsoft for paying attention to and creating a robust upgrade system throughout their years of developing Windows.  I personally never feel comfortable doing upgrades on my own computers; A fresh install always feels more proper.  I do know of some people who could never deal with the reinstalling and resetting of preferences and would opt for doing an upgrade.

What are you own experiences?  Have you ever had a Windows upgrade go bad?  If so, what went wrong?