A computer running Linux with KDE and OpenOffice.org is not terribly difficult for the average office worker to operate, and is very similar to Windows.
The trickiest part is installing it, which these people aren't going to be doing.
I agree the office apps are not terribly complicated. In my life in the IT field though I know that office workers use their PCs in many ways outside of standard apps; to a sys admin's begrudgement might I add. You are generally correct, this will make the sys admin's job much more difficult.
^^^^^^^^^^^^^The trickiest part is installing it, which these people aren't going to be doing.^^^^^^^^^^^
Even that is easy. Just use Suse or Fedora. I'm sure there are plenty others which are graphical install.