Windows 2008 R2 AD has a build-in feature ADMGS (Active Directory Management Gateway Service) to enable administrators to use the Active Directory module via PowerShell, but Windows 2003 SP2 and 2008 SP2 AD does not have it. Microsoft has released ADWS (Active Directory Web Services) for 2003 SP2 & 2008 SP2 to make it possbile for those AD administors.
Adagin, Microsoft blurs us one more in the name – ADMGS via ADWS.
ADWS is availabe to download from here.
Active Directory Administration with Windows PowerShell – http://technet.microsoft.com/en-us/library/dd378937(WS.10).aspx
AD Powershell module – Features:Remote Server Admin tools -> Role Admin Tools -> AD DS and AD LDS Tools -> AD DS Tools
Active Directory Web Services (ADWS) and Active Directory Management Gateway Service (ADMGS)
Active Directory Powershell Blog