Microsoft is gearing up to release 12 security bulletins Tuesday that will include patches for critical vulnerabilities in Office, Windows, Internet Explorer, VBScript, JScript and Visual Basic. The updates, which will come in Microsoft's monthly Patch Tuesday release, February 12, 2008.
The critical vulnerabilities all cause remote code execution problems. That means if the flaw is exploited, a hacker could remotely control the infected machine. The vulnerabilities rated important also cause remote code execution, which generally garners a critical rating.
News source: Microsoft Security Bulletin Advance Notification for February 2008 @ Microsoft Technet