Microsoft pulled a fast one. The definitions for the Standalone System Sweeper from MS Dart 6 used to be at http://go.microsoft.com/fwlink/?LinkID=96776, but now only Forefront, Microsoft Security Essentials and Windows Defender are listed. In fact, the definitions are the same for Microsoft Security Essentials and the Standalone System Sweeper. The file you want to download is mpam-fe.exe.
– Soli Deo Gloria