There are many good VBscript books out there.
For beginners, this is probably one of the best ones (IMO):
Microsoft WSH and VBScript Programming for the Absolute Beginner – Jr Jerry Lee Ford.
However, I think it doesn’t include more advanced topics such as the Active Directory Services Interface (ADSI), which would be useful for administrators. You might want to search for a book that covers ADSI and WMI, but make sure it includes any new features introduced with Windows server 2008.