Microsoft has an updated security bulletin search at http://www.microsoft.com/technet/security/current.asp
Some of the new features are:
Search enhancements: o Filtering by patch severity (Critical, Important, Moderate, Low) o Ability to search for patches that have not been replaced by more recent patches. o Ability to search for bulletins released within certain timeframes (last 6 months, year...etc) Enhanced search results data: o Affected software o Patch replacement information o Affected service packs o Max severity rating of the security bulletin Enhanced Results: Results now include bulletins that contain patches for the product/technology and service pack searched on, as well as the products shipped in the box with it. If Windows is searched for, the search returns bulletins with patches for Windows, as well as Internet Explorer and other related products/technologies.