Reliability and security quoted the main reasons for Linux switch
The majority (54% of respondents) said, they will leave their Windows server intact, though 25% reported they will migrate ‘a portion’ of their Windows servers to Linux for specialized application tasks. The chief allure of Linux at this point is not surprisingly the fact that many customers like the idea of ‘free’ licenses. Some 30% said they feel Linux is more reliable than Windows and 31% said they feel Linux is more secure than Windows, while another 29% expressed fears of being locked into an ‘all Microsoft environment.’
A majority of large enterprises with 5,000+ end users said they will not install Linux as their primary server OS in the foreseeable future because it is much more expensive and requires from 25% to 40% more Full Time Equivalent (FTE) support specialists than Windows or Unix for that matter.