Sysinternals Diskmon 2.01

Sysinternals Diskmon is a Windows system application that logs and displays all hard disk activity. It can be minimized to the system tray, where it acts as a disk light, showing a green icon when there is disk-read activity and a red icon when there is disk-write activity.

DiskMon is an application that logs and displays all hard disk activity on a Windows system.
You can also minimize DiskMon to your system tray where it acts as a disk light, presenting a green icon when there is disk-read activity and a red icon when there is disk-write activity.