from an MSDN flash I received:
Most likely you have heard about the “Slammer” Worm last week. While many communications focused on patching SQL Server 2000, there are additional Microsoft products used by developers which are affected.The worm targets MSDE 2000, which is installed as an integral or optional component of many Microsoft products including the .NET Framework SDK, Visual Studio .NET 2002, ASP.NET Web Matrix, Biz Talk Server 2002 Partner Edition, Host Integration Server, and some instances of Windows Server.