Ubuntu Brain Transplant – How Far Back Can I Go?

I like having a good backup strategy and thus have a couple of Clonezilla images of my notebook's SSD. In case my notebook gets lost or stolen I can restore the image on a backup drive, overwrite the data partition with the latest weekly backup and put the result in another notebook and I'm up and running again in no time. The question I had, however, was how close the hardware of the replacement notebook must resemble that of the original hardware for Ubuntu to still be usable.

To find out just that I recently restored a Clonezilla image of the SSD of my PC to a backup drive and installed that in a 4 year old notebook with completely different CPU and graphics hardware and a 6 year Atom based notebook, again with a very different processor, GPU, screen, touchpad and Wi-Fi hardware. That can't possibly work now can it!? Wrong! My Ubuntu 12.04 installation booted and ran perfectly on both systems. Graphics worked, the touchpad worked, the Wi-Fi worked, suspend/resume worked, everything just worked, I could hardly believe it.

Now try that with a Windows installation…