You can find useful information about sysinternal on the microsoft website.
There is six major topics displayed below. I only speack about
Utilities for viewing and monitoring file and disk access and usage.
Networking tools that range from connection monitors to resource security analyzers.
Utilities for looking under the hood to see what processes are doing and the resources they are consuming.
Security configuration and management utilities, including rootkit and spyware hunting programs.
Utilities for looking at system resource usage and configuration.
A collection of diverse utilities that includes a screen saver, presentation aid, and debugging tool.