KB936339 Windows-based computers are not displayed in the Network Topology diagram view in System Center Essentials 2007, and WSUS component parts fail on the Essentials 2007 agents after you deploy the agents has been released and is available http://support.microsoft.com/kb/936339

A hotfix for System Center Essentials 2007 is available for this problem.

 

The hotfix may be requested via online submission via http://support.microsoft.com/kb/937470/en-us