Microsoft® SQL Server™ version 7.0 provides a variety of tools that can be used to monitor the performance of a computer running SQL Server and the user activity that occurs in databases. Monitoring is an important task that allows you to determine if your database application is working efficiently and as expected. As your application, database, and environment change, regular monitoring allows you to check that these elements continue to work efficiently and to identify any areas that need modifying. For example, as more concurrent users use a database application, the load on SQL Server can increase. By monitoring you determine if the current SQL Server or system configuration must be changed to handle the increased workload, or if the increased load is having no significant effect on performance and therefore does not require any configuration change.
Monitoring SQL Server or the system environment requires:
Overview of Optimizing Database Performance