Windows and Linux...both OS have the own ability to serve. As today, all of body want the hosting in cheap prices. But with windows its unable to give. As apart from windows, Linux is open source and available freely like as centos and Ubuntu etc.. So these also effect the market.
As today starter user see the low price value option and then go for the Linux, Apache, MySQL, PHP (LAMP). All of these like PHP, apache, MySQL is free so its price is down.
But if we tell about windows.. then high end user demand it. to use with ASP .NET, MS-SQL etc...So windows required high - performance servers. So its cost is high...
and may be this reason people like Linux..