GPMC is a package which allows you to add handy GPO management snap-in to MMC.
If during installation you get an error:
Please install Microsoft .NET Framework before installing Microsoft Group Policy Management Console with SP1.
Then download and install Framework .NET 1.1 to your computer. Even if you have Framework 2 or 3 installed.
Same thing with WSUS snap-in. To add it into your MMC console you need to download full Windows Server Update Services 3 package from here and select only console during installation. Then you will find WSUS snap-in in MMC.
Active Directory snap-in is not accessible by default in Windows XP MMC. Firstly you need to install Windows Server 2003 Administration Tools Pack which is installable on Windows XP SP1. Here is the link.
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