All you do is to copy these three lines into a file called NOAUTRUN.REG (or anything.REG) and double-click it. Corporate network people can transform it into a script for their favourite command-line registry manipulator, or maybe make it a system policy thingy.

REGEDIT4
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\IniFileMapping\Autorun.inf]
@="@SYS:DoesNotExist"

This hack tells Windows to treat AUTORUN.INF as if it were a configuration file from a pre-Windows 95 application. IniFileMapping is a key which tells Windows how to handle the .INI files which those applications typically used to store their configuration data (before the registry existed). In this case it says "whenever you have to handle a file called AUTORUN.INF, don't use the values from the file. You'll find alternative values at HKEY_LOCAL_MACHINE\SOFTWARE\DoesNotExist." And since that key, er, does not exist, it's as if AUTORUN.INF is completely empty, and so nothing autoruns, and nothing is added to the Explorer double-click action. Result: worms cannot get in - unless you start double-clicking executables to see what they do, in which case, you deserve to have your PC infected.