Zotob is a worm that targets Windows 2000–based computers and takes
advantage of a security issue that was addressed by Microsoft Security
Bulletin MS05-039. This worm and its variants install malicious
software, and then search for other computers to infect.
From the page where you download the patch for the Plug 'N' Play
vulnerability:
Affected Software:
Microsoft Windows 2000 Service Pack 4
Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
Microsoft Windows XP Professional x64 Edition
Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service
Pack 1
Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft
Windows Server 2003 with SP1 for Itanium-based Systems
Microsoft Windows Server 2003 x64 Edition
Non-Affected Software:
Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and
Microsoft Windows Millennium Edition (ME)
So, maybe Zotob currently does not affect anything but 2000, but
according to this, the vulnerability exists to affect any modern NT
based OS. The worm may have already been altered, either by it's author,
or by other individuals.