Yesterday Microsoft released the final version of System Center Capacity Planner 2007.
System Center Capacity Planner 2007 is a pre-deployment capacity planning and post-deployment change analysis solution that provides best-practice guidance and hardware-specific knowledge to help information technology professionals make solid architecture decisions when planning a new deployment or changes to an existing deployment for Microsoft Exchange Server 2007 and other Microsoft server products as add-in application models become available.
Unfortunately :
Add-in knowledge for Microsoft System Center Operations Manager 2007, Microsoft Windows® SharePoint Services 3.0, and Microsoft Office SharePoint® Server 2007, coming soon
Download : Microsoft.com/downloads
Web site : Microsoft.com/systemcenter/sccp (not updated yet for the final release)