XP when I started going main on Linux. Windows 7 was the last version I had installed for games on a dual boot. Linux was always just more fun. I always felt like it was my computer and I wasn't constantly fighting the computer to make it work for me. Going to a tiling window manager was the point of no return though, my workflow changed so much that my productivity outside a tiling window manager plummeted.
XP when I started going main on Linux. Windows 7 was the last version I had installed for games on a dual boot. Linux was always just more fun. I always felt like it was my computer and I wasn't constantly fighting the computer to make it work for me. Going to a tiling window manager was the point of no return though, my workflow changed so much that my productivity outside a tiling window manager plummeted.