Microsoft has released the Windows Server 2003 Server Performancce Advisor, a server performance diagnostic tool developed to diagnose root causes of performance problems in a Microsoft® Windows Server™ 2003 operating system, particularly performance problems for Internet Information Services (IIS) 6.0 and the Active Directory® directory service. Server Performance Advisor measures the performance and use of resources by your computer to report on the parts that are stressed under workload.
download the tool here