In its security bulletin summary for February 2008 Microsoft has published six updates for new critical vulnerabilities in its operating systems / applications as well as five important.

Critical is Microsoft’s highest vulnerability rating.

A summary describing briefly the vulnerabilities is available from Microsoft’s Security Bulletin Summary for February 2008.
From this page you will also find links to more detailed information in Microsoft's Security Bulletins MS08-003 - MS08-013.

The critical updates address the following issues:

• One privately reported vulnerability in WebDAV Mini-Redirector
• One privately reported vulnerability in OLE Automation
• One privately reported vulnerability in Microsoft Word
• Three privately reported and one publicly reported vulnerabilities in Internet Explorer
• Two privately reported vulnerabilities in Microsoft Office Publisher
• One privately reported vulnerability in Microsoft Office

The update for Internet Explorer is probably the most crucial as this also addresses one vulnerability that is disclosed to the public.

Updates that fixes the vulnerabilities are available from Windows automatic update mechanism for systems that support this. Alternatively, one may download updates from http://windowsupdate.microsoft.com.  

Norman advices all affected users to download the security updates as soon as possible, to be protected from potential exploits.