If you are a server admin you will want to check out the recently released Microsoft Windows Server 2003 Server Performance Advisor (SPA) available here.
SPA is a server performance diagnostic tool developed to diagnose root causes of OS performance issues Windows Server 2003 operating system, particularly performance problems for Internet Information Services (IIS) 6.0 and the Active Directory directory service. Neither Microsoft Windows XP nor Microsoft Windows 2000 supports this tool. Server Performance Advisor measures the performance and use of server resources that are stressed under workload.
Other server roles include system overview (hot files, hot TCP clients, top CPU consumed), print spooler, context switch data and preliminary File Server trace data.