The following tools are used to monitor SQL Server:
SQL Server Enterprise Manager
SQL Server Profiler
The System Monitor is a Windows 2000 tool for monitoring SQL Server and the Windows NT operating system (Windows NT 4.0 has a similar tool named Performance Monitor). The advantage of the System Monitor is that it is tightly integrated with the operating system. This enables you to track real-time statistics about SQL Server and Windows NT. Together, these statistics can be used to isolate bottlenecks and track performance.
The System Monitor might slightly degrade system performance on older machines. The overhead incurred from the System Monitor has been found to be 5% or less ...