The windows server 2003 performance advisor, http://www.microsoft.com/downloads/details.aspx?familyid=09115420-8c9d-46b9-a9a5-9bffcd237da2&displaylang=en, was recently (7/3/2008) updated. It's a great tool for analyzing servers and determining when you might need to scale it out. It can track major counters over time and provide recommendations relating to performance. If you have thresholds for your web applications this will give you a great idea when to scale out.
Overview
Microsoft ® Windows Server ™ 2003 Performance Advisor is the latest version of Server Performance Advisor, which is a simple but robust tool that helps you diagnose the root causes of performance problems in a Microsoft Windows Server 2003 deployment. Server Performance Advisor collects performance data and generates comprehensive diagnostic reports that give you the data to easily analyze problems and develop corrective actions
Microsoft ® Windows Server ™ 2003 Performance Advisor provides several specialized reports, including a System Overview (focusing on CPU usage, Memory usage, busy files, busy TCP clients, top CPU consumers) and reports for server roles such as Active Directory, Internet Information System (IIS), DNS, Terminal Services, SQL, print spooler, and others.
