In Win9x, it was c:\windows\desktop etc., before windows became multi-user, when it moved to c:\windows\profiles\xxx\desktop and later to C:\Users\xxx\Desktop. But only on US installations, in international versions it was c:\benutzer\xxx\desktop or whatever the translation of "users" was. That is until windows 7 (I think) when they moved to the English name for all systems, and had the UI (Explorer) translate it, which led to strange issues that Explorer shows "C:\Benutzer\x\Desktop" while the command prompt shows "C:\Users\x\Desktop"

On some versions it was also "C:\Documents and Settings\...", it is so convoluted that even I don't remember all the specifics, but yes, it was a total mess, especially on non-english installations