When you run the Microsoft Baseline Security Analyzer version 1.2 in default mode, it downloads the Mssecure.cab file for the language of the computer that is being scanned, and extracts a localized XML file for use in the scan. MBSA reports the security updates that have not been installed, the superseded or outdated updates.
When you run MBSA V1.2 with the SUS option, it uses the local SUS server's list of approved updates, instead of the Mssecure.cab file. It reports all the missing updates, even if the have been superseded. You do not have to install these extra updates.