I saw that you still have 2k running - I skipped that too!
Let's see: DOS (I can't remember version when I started, but it was early - had Word 1.0 and two 5-1/4 floppy drives!) - once I got the hang of things, I dumped MS DOS and went with DR DOS, much better; win 3.0; win3.1 (I hated both Windows and stayed with DOS for a long time - had a "task switcher" that would allow me to "multitask" in DOS); Win 95; Win98, then SE; XP; Vista.
I think that 98SE was my favorite of all time.