In Windows Vista Microsoft had a feature called reliability and performance monitor which helped us track on the usage of our computers resources such as hardware, software etc.
In Windows 7 this particular tool has been enhanced tremendously and named as resource monitor. You can start this tool by clicking on the windows button (start) and typing resmon in the search box.
The resource monitor gives detailed information on how your hard disk, memory, processor and network is being used.
The Resource monitor is an advanced version of the traditional task manager and here you will get much more descriptive information. This information goes to an extent where you will be able to see detailed I/O information of your hard disks activity.
When you click on the Network tab in the Windows 7 Resource Monitor it gives you a very much detailed information where it shows the network processes, network activity, listening ports etc.