"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..."