With the release of products Windows Server 2008 and Windows Vista SP1 Microsoft removed the old management tools and other features that shipped with RTM Windows Vista. When you install Service Pack 1(SP1) on Windows Vista you will notice that the Group Policy Management Client (GPMC.msc) and other Windows features are no longer available in the operating system.This is because these Windows features have been uninstalled or removed permanently from your system after installing Windows Vista Service Pack 1(SP1).
Microsoft replaced the old utilities and features of Windows Vista with updated version in the Remote Server Administrative Tools (RSAT) package.You can download the Remote Server Administrative Tools (RSAT) from the links given here.

Download the 32-bit version for Vista SP1
Download the 64-bit version for Vista SP1

Once you have downloaded and installed the Remote Server Administrative Tools (RSAT) in Windows Vista you need to turn these features on.The steps for this is given below:

• Open Windows Vista Control Panel and go to Programs and Features.
• Click on the option Turn Windows features on or off located on the side menu.
• Check Remote Server Administrative Tools and hit OK.