The Microsoft's Chief Securty Advisor for Italy, Feliciano Intini, has recently compiled this page in his blog, collating all the current Microsoft-related security blogs in one page, which is probably quite a useful reference when you are searching for Microsoft security information. Take a look here: http://blogs.technet.com/feliciano_intini/pages/microsoft-blogs-and-web-resources-about-security.aspx.