The first use of the phrase "windows box" was during the development of the graphical user interface (GUI). In the 1960's computer science researchers such as Douglas Engelbart experimented with software and hardware to increase computer user productivity. Among the ideas developed were hypertext, the "mouse," and the concept of computer graphics windows.
The first "windows boxes" were specialized "graphics boxes" with a user interface that included windows (rectangular regions displayed on a computer screen that contain information different from what is on the rest of the screen). Although Macintosh computers were the first mass-market computers to use a window-based GUI, Macintoshes were never known as "Windows boxes," which is used almost exclusively to describe computers that run Microsoft Windows. The phrase "windows computer" was also used to distinguish such GUI computers from earlier "Command line interface" computers such as the original 1981 IBM personal computer.
Microsoft Windows 1.0 was released to market in November 1985, but the Windows operating system had little impact before Windows 3.0 in May 1990. 1990 was the year that the first  webpage went online. At that time, various text pages on the internet document use of the term "UNIX box". Example:
Within a few years, mention of "windows boxes" began to appear on the internet:
Use of the term "windows box" on the internet has always trailed behind other phrases such as "windows machine", "windows computer", and "windows PC" but the use of "windows box" increased steadily during the 1990s as the Microsoft Windows operating system matured.
1997. Gag gift "windows box". The Windows9x crashbag box could be mounted on a computer monitor. It had a warning on it saying that it would inflate a protective airbag if you banged your head on the monitor when Windows kept crashing.
Finally, in 2003 use of the term "windows box" on the internet reached levels comparable to use of the term "UNIX box".