The IE Cumulative Security Update for April 2009 is now available via Windows Update or Microsoft Update, is rated Critical for Internet Explorer 5.01 and Internet Explorer 6 Service Pack 1,  Internet Explorer 6, and Internet Explorer 7 running on all supported editions of Windows 2000, Windows XP and Windows Vista.  For Internet Explorer versions running on all supported editions of Windows Server 2003 or Windows Server 2008, the update is rated Important.  For Internet Explorer Beta products, download locations are available in the Knowledge Base Article.