Available via Software Update:
QuickTime 7.1.2 addresses an issue previewing iDVD projects. This update is recommended for all QuickTime 7 users.
Important Notice to QuickTime Pro Users
Installation of QuickTime 7 will disable the QuickTime Pro functionality in prior versions of QuickTime, such as QuickTime 5 or QuickTime 6. If you proceed with this installation, you must purchase a new QuickTime 7 Pro key to regain QuickTime Pro functionality. After installation, visit www.apple.com/quicktime to purchase a QuickTime 7 Pro key.
Or download from Apple's website: http://www.apple.com/support/downloads/quicktime712.html