(per the doc/download page) "This update provides important issue fixes and is recommended for the aluminum 20-inch and 24-inch iMac models with 2.0, 2.4, or 2.8 GHz processors. Requirements: Mac OS X 10.4.10, iMac (Mid 2007)" If you were an AL iMac owner with system freezes in Tiger previously (reported on the AL/2007 iMac reports page) and this update solves it, let me know.