Linux Foundation survey on enterprise Linux use
In short, the survey found that Linux is poised for growth in the coming years; 76.4% of companies are planning to add more Linux servers in the next twelve months. In contrast, only 41.2% of respondents are planning to add Windows servers in the next year, while 43.6% say they will be decreasing or maintaining the number of Windows servers in their organizations over the same time period." Registration is required to obtain the full report.