First OS: I think it was Windows 98. I have then gone through XP, Vista, 7 and staying at 10 for as long as i can.
First Linux distro: Ubuntu 10.04 or 10.10 don't remember clearly but it certainly was before GNOME 3 and in a VM. From then i have also run Fedora, Debian and most recently Linux Mint and Pop! OS in VMs as well. Maybe one day i finally set up a dual boot...