Via Mark Harrison:
"The SharePoint Capacity Planning Tool v1.0 is now available.
The SharePoint Capacity Planning Tool is a set of free models of Windows SharePoint Services 3.0 (WSS) and Microsoft Office SharePoint Server 2007 (MOSS). The two models use the analysis and simulation features of System Center Capacity Planner 2007 (SCCP) to help you explore suitable IT infrastructure options for your SharePoint deployment, based on the SharePoint usage requirements for your organization that you provide to the tool. It can give you a head start on planning your SharePoint topology by producing a first approximation of the topology your organization needs. Architects, systems integrators, and deployment engineers will find it to be a valuable starting point for further refinements of the topology.