Windows Server 2008 is a supported platform for the Essentials 2007 SP1 Server, Console and Agent
Essentials 2007 SP1 management server, console and agent on computers running Windows Server 2008 will be fully supported by CYQ208. Management packs for Windows Server 2008 and it's role will be available as well in the same timeframe.
Microsoft Windows Server 2008 is the next generation of the Windows Server operating system and provides significant improvements to the base operating system over Windows Server 2003. Notable improvements include those in networking, advanced security features, remote applications access, centralized server role management, performance and reliability monitoring tools, failover clustering, deployment, and the file system. Because of these improvements to the base operating system, backward compatibility of all applications could not be ensured.
Information on upgrading to Server 2008 http://technet2.microsoft.com/windowsserver2008/en/library/bab0f1a1-54aa-4cef-9164-139e8bcc44751033.mspx?mfr=true