Microsoft has recently released an add-in for Visio to help you build rack diagrams.
Rack Server Virtualization Add-in provides the capability to pull the rack-server data either from an Excel spread sheet or from the user and render the Visio diagram. The Add-in from Microsoft Office Visio 2007 Professional helps you plan virtualization and draw a clear picture of your hardware utilization.
This tool auto-generates the diagram of your rack and provides clear server details from a linked Excel template. Analyze your racks and servers using WMI or get the utilization data over time using the Operations Manager connection.
Use the virtualization button to see the before and after detailed diagram of your racks. See clearly where you have the opportunity to save on space and power.