What is the oldest Windows operating system to run on a modern (2007-2009) computer? [closed]

"If you have any sort of virtualisation product installed, there is no limit!

I have messed around with Windows Disk Operating System (before it had a version number!), and many other systems that are 20+ years old.

If you are willing to take out some RAM, you can get Windows 3.1 working no problem on modern hardware - It will work with the extra RAM, but HIMEM.sys can take an age to complete on a high end modern system!

I know you can go earlier than that, but without any sort of hack and just the standard disks, I think that Windows 3.1 / Dos 6 is probably the easiest to install early OS that anyone can mess around with."

The easiest way to run such an OS is to use a VM. I've run Windows 95 in a VM with almost no problems. Unfortunately, the network card was nowhere to be found, so no internet for me. Windows 98 and up should not be such a major problem.

"Would you be happy to just see a successful install?
Or, would you also want it to be usable for daily activities?

The primary problem I see with such exercise is the lack of driver support for older Windows versions.

If you use a VM platform the driver problem might get resolved to some extent.

If might be more fun to check out some Linux distributions
(which btw you can do even with USB booting flash drives)."

Why not run the oldest computer ever on it? (Not strictly an operating system)