Microsoft has released an update for Windows Vista to restrict AutoRun entries in the AutoPlay dialog to only CD and DVD drives.
Update to restrict AutoRun
AutoRun is the ability for a device, through the use of autorun.inf, to expose a set of tasks for the user to choose upon insertion of new media into the computer. This could be a USB drive, a CD or DVD, a network drive, or any other additions of new media. The user is shown the AutoRun tasks along with other functions via the AutoPlay dialog.
Autorun is different form AutoPlay. Autorun is used to start some programs or enhanced media content automatically when you insert a CD, DVD or another media type into your computer. AutoPlay lets you choose which program to use to start different kinds of media, such as DVD, CD, etc, containing music, video, photo, etc.
Due to a rise in malware usage of the AutoRun system, the Windows 7 team has undertaken a dramatic step to block this specific threat.
To restrict AutoRun entries in the AutoPlay dialog of Windows Vista, please download & apply the patch available at KB971029.
Microsoft has made some changes in AutoRun feature in Windows 7. You might want to read this post too.