Windows server 2003: stop the use of specific password?

I would like to prevent users from changing their Windows login passwords to something too obvious, for example their own name. We already use the Windows Server 2003 group policy to specify password minimum length, age and complexity.

How do we stop certain words, in whole or part, being selected by the user?

For example for me I would not want my name, Sam, to form any part of the password.