In its security bulletin summary for February 2007 Microsoft reports a total of six new critical vulnerabilities in its operating systems / applications, as well as six important ones.

Critical is Microsoft’s highest vulnerability rating.

A summary describing briefly the vulnerabilities is available from Microsoft’s Security Bulletin Summary for February 2007.
From this page you will also find links to more detailed information in Microsoft's Security Bulletins MS07-008 - MS07-010 and MS07-014 - MS07-016 (critical) and MS07-005 - MS07-007 and MS07-011 - MS07-013 (important).

The most serious of the vulnerabilities address are probably those described in the MS07-0014 which have to do with several vulnerabilities in Microsoft Word. We refer also to our Security Advisory regarding this.

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.