Some of this is covered in Andrew Grygus's article 2003 and Beyond:

    http://www.aaxnet.com/editor/edit029.html

Andrew writes:

"Then, in December 2002, Microsoft about faced again, saying Windows 
has  lower TCO (Total Cost of Ownership) over a 5-year period, and 
cited an  IDC study which Microsoft paid for.  Problem with the study 
is, nobody believes it. It not only contradicts  established 
experience, but has flaws obvious even to the untrained eye.  Further, 
one of the authors is on record saying Microsoft's conditions biased  
the study."

"The study presumes: Linux installations need as many administrators as 
  Windows installations (they certainly do not), and Linux 
administrators cost a  lot more than Windows administrators (they do 
not). Completely omitted are  the cost of major Windows upgrades, which 
are required by License 6,  every 3 years. Windows 2000 Server is the 
5-year baseline, and it's only been  out 2 years, so figures are just 
projections."

"Microsoft is keeping the full study and its methodology secret and  
releasing only summary figures. This suggests there are many more  
questionable assumptions and a lot more twisted logic in there."

Andrew has some more insights into Microsoft's marketing strategy and 
why he believes Businesses will most often choose Microsoft.

-Stephen