How to Upgrade Hyper-V beta build ?

If you are thinking to upgrade your Hyper-V beta build from Windows Server 2008 RC1 to Windows Server 2008 RTM then follow below steps:

1. Shut down all virtual machines that are currntly running.
2. Using Hyper-V Manager console,export the virtual machines and the configuration files to a data volume.
3. Format the volume where the operating system is and after that install the Windows Server 2008 RTM build.
4. Using server manager install the Hyper-V role.
5. Now start the virtual machines and then start upgrading the integration components.

For more details about this please visit link below:
http://technet2.microsoft.com/windowsserver2008/en/servermanager/virtualization.mspx