After installing this update the new version number (4.0.2165.594) won't appear in the ISA management console configuration dialog (instead it will show SP1 4.0.2163.213).
To find the installed version in the mmc click help->about or go to Add/Remove programs and click "Click here for support information" under the ISA 2004 SP2 item.
ISA Server 2004 rtm: 4.0.2161.50
ISA Server 2004 SP1: 4.0.2163.213
ISA Server 2004 SP2: 4.0.2165.594