This month Microsoft released six security bulletins, three of them rated Critical, three of them rated Important.

The three Critical bulletins are:

1. Vulnerabilities in the Embedded OpenType Font Engine Could Allow Remote Code Execution (961371)
2. Vulnerabilities in Microsoft DirectShow Could Allow Remote Code Execution (971633)
3. Cumulative Security Update of ActiveX Kill Bits (973346)

The three Important bulletins are:

1. Vulnerability in Virtual PC and Virtual Server Could Allow Elevation of Privilege (969856)
2. Vulnerability in Microsoft ISA Server 2006 Could Cause Elevation of Privilege (970953)
3. Vulnerability in Microsoft Office Publisher Could Allow Remote Code Execution (969516)

You can find more information here on the Microsoft site.

Here's a summary of the patches released so far in 2009:

The use of unpatched vulnerabilities continues to be a significant part of the threat landscape, so it's important to make sure you patch your systems. Remember you can use Windows Automatic Updates to automate this process.