How to Activate Windows 2008 Servers with Volume Licensing Keys

When you use volume-licensed media to install Windows Vista Enterprise, Windows Vista Business, or Windows Server 2008, the installation process uses a generic product key. When you then try to activate Windows Vista or Windows Server 2008, the activation wizard uses DNS to locate a Windows Vista-based or Windows Server 2008-based computer that is running the KMS software. When the wizard queries DNS and does not find the DNS entry for the KMS host computer, the wizard reports the error message. If you have a KMS computer set up, the correct DNS entries are not seen by the client computer. If you do not have a KMS host computer set up, you must either set up a KMS host computer or switch to a MAK product key method to activate your volume license installation.
Click Start
click All Programs, click Accessories, and then right-click Command Prompt.
Click Run as administrator.

At the command prompt, type the following command, and then press ENTER:
slmgr -ipk xxxxx-xxxxx-xxxxx-xxxxx-xxxxx

(substitute the Volume licensing KEY for the x's in the command)