The following was taken from a Microsoft corporate blog designed to document the history of Microsoft.
When I joined Microsoft as Vice President of Corporate Communications, I came from the cosmetics / skin care industry where perception (branding) was far more important than reality. The branding strategy for Microsoft Corporation & the specific names for the products (which was part of the company branding strategy) came from the original branding strategy developed & executed at Neutrogena Corporation. Along with identifying & nurturing the support of industry opinion leaders, pithy, generic-like, names were selected in order to force the usage of the company name in editorial etc.
For example, prior to being well known as a word processing program, the name “Word” could not stand alone in editorial…..the editors felt compelled to put the company name in front of the name “Word” in order to identify the company origin (unlike a word processor called WordStar which never required the company identity). With regard to WINDOWS, we were actually fortunate to be late with our GUI introduction. Other GUIs had been launched so we were able to review how the opinion leading editors were describing them. The common description of GUIs @ that point of time was that they were “windowing systems” for your desktop. Therefore, if all these GUIs already launched ahead of the Microsoft GUI were being described as “windowing systems”, the most logical & most generic-like name we could call our GUI was “Windows”.
Post reaching agreement on this name internally, the challenge was to successfully introduce it at Comdex. This was achieved by a fantastic team of individuals…Pam Edstrom, Tricia McGinnis (now Tricia Raikes), Eileen Gunn, to name a few. Today “Windows” is a dominant stand alone brand name but back in the early 80s it was normally referred to as Microsoft Windows, not just Windows, because the editorial community felt a need to be clear that they were writing about Microsoft Windows & not one of the other “windowing systems”.
Here is a little more insight into why the names Windows & Word were selected and the overall impact.
In the early 80s, our goal was to establish Microsoft as the quality brand / the trusted brand in software. Establishing trust / confidence in a company brand makes every new product introduction from a company more efficient & more effective. Think of classic examples in major categories like cars (ie Mercedes) or even skin care (ie Neutrogena). Regardless of the new car Mercedes or new skin care item Neutrogena may introduce, most consumers already believe the claims the company makes about the new product because of the trust factor they have with these brands.
In the early 80s we knew if we could establish the “trust factor” for Microsoft in software, it would go a long way to helping us dominate the category (even if we were not always first in with an application and / or even required multiple updates).
To achieve this, we executed three primary communication strategies:
1) Thru research, we identified the essential things software buyers needed to know / believe about Microsoft in order for them to position Microsoft in their mind as the quality brand / trusted brand in the category. We then highlighted these things about the company in all communications…..from product brochures to press releases to instruction manuals…..they all delivered the company mantra.
2) We identified the opinion leaders within the software industry (ie key editors, user groups, heavy software users, etc.) & then we devoted a disproportionate amount of resources to influencing these opinion leaders. Once the opinion leaders in a category trust a brand, it is only a matter of time for the consumers in a category to do the same.
3) And, last but not least, we executed the naming strategy that resulted in the company brand, Microsoft, being essential in all communications on all products. As I mentioned in a previous post, individual product names like Windows & Word were designed to have the company name, Microsoft, proceed them.
In the 80s, we measured “awareness & attitudes” about Microsoft among targeted opinion leaders & consumers every 6 months. Thru this monitoring, the impact of these communications strategies became clear. While awareness of Microsoft went up, more importantly, the attitudes about Microsoft among those “aware consumers” also changed. Microsoft software became the preferred brand among consumers in general; not just among highly technical users.
We always said internally that we would know our branding strategy was successful when consumers started asking for the Microsoft brand regardless of application and that began happening in the late 80s.
For you to understand why “Windows” was named “Windows” you need to know that we had a “master plan” for branding. As I explained, with regard to WINDOWS, we were actually fortunate to be late with our GUI introduction. Other GUIs had been launched ahead of us so we were able to review how the opinion leading editors were describing them. The common description of the GUIs @ that point of time was that they were “windowing systems” for your desktop. Therefore, if all these GUIs already launched ahead of the Microsoft GUI were being described as “windowing systems”, the name “Windows” became essential; not optional. In other words, rather than just being another “windowing system” (me too strategy), in one announcement / pivotal name selection we re-positioned all the existing “windowing systems” as being part of us (ie we defined the category & everybody else reinforced our selected name).
The name, Interface Manager or at times Interface Office Manager, was actually a code name that got some initial internal traction in absence of a “final name” that took a little time to determine in parallel to the actual GUI development process.
How you “name” a product needs to take into account both your company branding strategy & your desired category positioning of the product. It should never be a random decision but many times it is because the broader implications are not considered 
Since contributing to this blog I have received several e-mails / calls all interested in additional clarification / explanation on the original Microsoft, Windows, & applications branding strategy as well as how we actually launched Windows. There are an amazing number of rumors / misunderstandings regarding what we did, when we did it, where we did it, & who it influenced. To avoid another long post, if you are interested, you can go to an excerpt from one of the more accurate books on the history of Microsoft; “Barbarians Led by Bill Gates.“