RSAT (Remote Server Administration Tools) is essentially the new version of Windows Server 2003 Administration Tools Pack - Adminpak.msi, for Windows Vista. The package allows you to remotely manage roles and features in Windows Server 2008 from a computer running Windows Vista with SP1. Yes, SP1 for Vista is required by RSAT.
Support for remote management is provided for both the Core Server and the full installation of Windows Server 2008. In addition, RSAT also includes an updated Group Policy Management Console (GPMC), which was previously removed in Windows Vista SP1.
As it is demonstrated in the Step-by-Step Screencast, if you are running a previous version of Server Administration Package (Adminpack.msi), you have to uninstall it first before you proceed with the installation of RSAT.
There is a x86
version of RSAT, so make sure that you download and install the corresponding version for your OS.