AnswerGFI LanGuard scans computers for "Security Updates" (I.E. patches that have bulletin IDs in the form of MSyy-nnn. Example: MS14-018) using Microsoft's "offline catalog" file. Therefore, it should match the results obtained by Microsoft's Baseline Security Analyzer (MBSA) tool.
In order to use the tool, do the following:
1. Download the MBSA from http://www.microsoft.com/en-us/download/details.aspx?id=7558
2. Run the tool installer - it will install to the local machine
3. Run the tool itself from the Start menu
4. Select the following options shown below and click the Start Scan button.