This free Silverlight Dreamweaver extension uses Silverlight 1.0 You must add the Silverlight.js file to the same folder as your webpage(s) running this player. You can get the free Silverlight.js file off of the www.Silverlight.net website by downloading the Silverlight 1.0 SDK.
As designer gone developer, I know many still use Dreamweaver for layouts, this is a great free tool that integrates with Visual Studio to help you get started with Silverlight.