I am a Systems Engineer working mainly with Windows for most of my career.
I am a Linux enthusiast and want to help SMBs move away from Windows and embrace Open Source, as a better option.
I started a business for just that purpose.
Other OSs I have experience with:
cp/m If you don't know this one, you can watch this https://www.youtube.com/watch?v=VCXIUOx9X1k&list=PLjSrL4-yAJ1FyBK5Ea4ZO0mD5caqKfY1H&index=2
It's long but well worth the watch.
DOS
Windows (3.1 to current)
Netware (3.1 to 5.0)
Linux (I have tried a lot, and have come to really enjoy Ubuntu)
HPiX