Althoug the Forefront Server Protection product team had already blogged about capacity planning, there is a new tool (Excel spreadsheet) available: Forefront Protection 2010 for Exchange Server Capacity Planning Tool.
The Forefront Protection 2010 for Exchange Server (FPE) capacity planning tool lets you understand the hardware requirements for planning new FPE deployments. It also lets you evaluate the system requirements for existing deployments.
The FPE capacity planning tool helps you understand how CPU utilization and memory requirements vary by specifying different protection settings of FPE. This tool is based on the capacity planning guidance provided for Exchange Server 2010. The FPE capacity planning tool uses two specific reference architectures, the Standard Reference Architecture which is targeted at the small to medium size customers and then the Enterprise Reference Architecture targeting larger organizations. You can select a workflow associated with a reference architecture and specify CPU utilization and maximum memory constraints for your targeted hardware. You can specify the desired protection settings for each of the FPE server roles in the associated reference architecture, and describe the desired environment to be supported. After all these items are specified, the tool produces a summary of the hardware requirements with the number of servers that should be utilized to support the targeted environment given the FPE protection settings and the specified hardware constraints. The tool also provides performance guidance using graphs to understand performance aspects of the product and comparative performance of virtualized and non-virtualized scenarios with different operating systems and Exchange versions.