The Forefront Security Development Team launched a new capacity planning tool. The Forefront Security for Exchange Server capacity planning tool helps you understand what hardware, architecture, and configuration settings will produce recommended system performance and message throughput results for comprehensive protection of your Exchange Servers. The tool is an Excel spreadsheet with built in workflow and can be used to help plan your Forefront Security for Exchange Server 10 SP1/SP2 deployment.

Microsoft Forefront Server Security Blog : Introducing the Forefront Security for Exchange capacity planning tool