Microsoft has just posted their security patch bulletin for the month of January. As usual, all required patches for your PC can be caught using Windows Update or Microsoft Update. A total of 4 patches were released this month including these 3 listed as "Critical":
MS07-002: Vulnerabilities in Microsoft Excel Could Allow Remote Code Execution - KB927198 - Critical
This update resolves vulnerabilities in Excel that could allow remote code execution.
MS07-003: Vulnerabilities in Microsoft Outlook Could Allow Remote Code Execution - KB925938 - Critical
This update resolves vulnerabilities in Outlook that could allow remote code execution.
MS07-004: Vulnerability in Vector Markup Language Could Allow Remote Code Execution - KB929969 - Critical
This update resolves vulnerabilities in Internet Explorer that could allow remote code execution.