How do I activate products using Volume Activation with KMS?
After you set up your KMS activation, by default both physical and virtual Windows Vista and Windows Server 2008 machines will attempt to activate by connecting to the KMS host.You must establish and maintain a minimum number of KMS client computers for activation to occur. You must have at least five (5) computers to activate Windows Server 2008 and at least twenty-five (25) computers to activate Windows Vista clients. Computers needed to meet the thresholds can be both physical and virtual.