New users are usually more comfortable with the icons and mouse associated with Windows than they are with the keyboard. Windows gives people the ability to run most applications that function in DOS without ever having to touch a keyboard for other than the entry of data. There are also many excellent menu systems that run under DOS that make the actual OS being used unimportant to the user. As a matter of fact, I would bet that if there was a poll taken of corporate employees using a menu system for DOS, most users would not know what OS they are actually running. The final factor to consider is the degree of technical support within an organization.
Some systems require more knowledge of computers than others.
But this would not be true for all OSs. For example, I would be very wary of a new user installing Unix. Such an installation would require someone with a little more computer experience. Similarly, the installation and daily running of a LAN requires someone with more technical knowledge than a novice. Some vendors lead people to believe that a LAN runs itself.