Check out http://silverlight.net/Default.aspx for more details.
Install links: (* = optional)
Orcas Beta 1 (http://msdn2.microsoft.com/en-us/vstudio/aa700831.aspx)
Silverlight 1.1 Runtime (http://go.microsoft.com/fwlink/?LinkID=88986&clcid=0x409)
Silverlight Tools for Orcas Alpha (http://www.microsoft.com/downloads/details.aspx?FamilyId=6C2B309B-8F2D-44A5-B04F-836F0D4EC1C4&displaylang=en)
*ASP.NET Futures (http://go.microsoft.com/fwlink/?LinkID=89147&clcid=0x409)
*Expression Blend 2 May Preview (http://go.microsoft.com/fwlink/?LinkID=79076&clcid=0x409)
With the tools you can create Silverlight Applications, link them easily to web applications, and debug. The ASP.NET Futures contains the new Xaml and Media controls, making it easy to use Silverlight in a web application (just drag-and-drop the Xaml file onto the designer). Expression Blend is a designer tool for building and editing Xaml, and with it installed the ‘Open in Expression Blend’ command becomes available (right-click on a Xaml file) allowing you to easily move between the two tools as you’re building a Silverlight application.
Questions or issues? Please post to the Visual Studio Silverlight forum – http://silverlight.net/forums/18.aspx.