Microsoft Windows’ one of the interesting feature was the Autorun feature that was responsible for the default action to be performed automatically whenever you insert a drive. Say you have inserted a USB pen drive and the default action for it was to open the contents, Autorun feature helped it to open the drive automatically.
However as you may know, this feature was also exploited the most by the virus makers. You must have known about the file created by virus called Autorun.inf. Thus seeing this vulnerability Microsoft had decided to shut down this feature.
This is the reason why you can’t see the Autorun feature in Windows 7 (however in case you are inserting a disk, you may see this feature in Win 7 as well). To disable this feature in the earlier version of the Windows, Microsoft had released a Windows Update KB971029 that disables the service in Windows 2000, XP and from Vista.
Although this is an optional update that is not necessary to be installed, we would recommend you to install if it lists in your Update list.