"There's a downside to adding Linux or Unix servers to a Windows shop: These orphan machines lie outside the protective umbrella of the centralized user authentication and authorization controls of Microsoft Active Directory. The result? Multiple user identifications and logins, higher risk of errors and security loopholes, and, of course, more work for system administrators.
"But, according to John Enck, a research vice president of Gartner Inc. probably less than 20% of mixed Linux and Windows shops use a single authentication and authorization vehicle that covers Windows and non-Windows machines..."