Released in 1983, several years prior to Windows, VisiCorp Visi On was the first GUI for the IBM PC.
This video shows Visi On running on the equivalent of a 4.77 MHz PC with 640k of RAM using MESS PC emulation. As such, opening and closing application is a little sluggish, but in 1983 this was blazing fast!
Several things to note: Overlapping windows, scrolling menus and property sheets, scrolling text windows with dragging, the ability to transfer data between programs, application specific help, hyperlinks to move between help topics, slightly longer file names that can include spaces and case, and lots of beeping.
This video shows Visi On Word, Visi On Calc, Visi On Graph, and the Archive Manager.
Similar to the Apple II desktop, I had to run this through a blur and sharpen filter to deal with the 50% gray.
MICROSOFT
Microsoft began developing a graphical user interface (GUI) in 1981. The development of Windows began after Microsoft founder Bill Gates saw a demonstration at COMDEX 1982 of VisiCorp's Visi On, a GUI software suite for IBM PC compatible computers. In 1983 Microsoft learned that Apple's own GUI software, based in part on Xerox PARC technology, was much more sophisticated, and decided that its own product would be different.