As you probably have seen this allready, as a reminder:

On 03 April 2007 Microsoft is planning to release:

One Microsoft Security Bulletin affecting Microsoft Windows. The highest Maximum Severity rating for these is Critical. These updates will require a restart. These updates will be detectable using the Microsoft Baseline Security Analyzer.

Advisory:
http://www.microsoft.com/technet/security/advisory/935423.mspx

http://blogs.technet.com/msrc/default.aspx
http://www.microsoft.com/technet/security/bulletin/advance.mspx

Urs