I remember poking around with an early version of Microsoft Windows in the late 1980's, definitely before the 90's. It was of limited functionality, though. Pokey and I don't remember any useful apps. It must have been version 1. It wasn't until 3.1 that it became minimally useful, and not until 95 did it actually enable one to be productive in an office. The MAC of course had already demonstrated the concept, but with an closed OS.
Windows 95 screwed up our local area network pretty good, with network shells that broke Netware. It was a nasty bit of commercial competition. Windows 98 was a bit better, Windows NT was Microsoft's attempt to dominate the local area network market, but fell far short, and Windows 2000 along with Active Directory finally became a power user's OS as well as a workable network file/print/application server. Novell no longer exists, RIP.