Task Manager is a new tool introduced with Windows NT 4.0 Server and Workstation. It lets you monitor active applications and processes on your computer, and start and stop them. Best of all, it has basic performance-monitoring capabilities and a friendly interface:
Task Manager gets its data from the same functions used by Performance Monitor. However, it calls these functions directly, bypassing the Performance Library and the registry. Thus, it cannot log data to a file and it cannot monitor remote computers. However, it is a useful tool for quick checks of basic counters and for training users to monitor their own computer.