Credit:
Apple has released security updates for the Windows version of Quicktime. You may remember that this particular Quicktime security flaw allowed for the handling of URLs in the qtnext field in files with QTL content. If these files were to be opened by a Quicktime user, an attack on the user's computer would ensue, rendering the malicious files enabled.
The security flaw has already been addressed by Firefox, and Apple's patch can be found here. The patch affects users of QuickTime 7.2 on Windows Vista, XP SP2, for the vulnerability found in CVE-2007-4673.