"According to the study, the three-year cost of a 100,000-hit
processing unit was significantly different among the systems: 
Solaris: $561,520
Windows: $190,662
Linux: $74,475"
	(A processing unit is the number of servers that would be
required to process 100,000 hits per day)
http://techupdate.zdnet.com/techupdate/stories/main/0,14179,2907876-3,00.html