Expression下载地址：
http://www.microsoft.com/expression/try-it/Default.aspx?filter=blend3sketchflowrc#PageTop
Silverlight™ 3 Tools for Visual Studio 2008 SP1
http://www.microsoft.com/downloads/details.aspx?displaylang=zh-cn&FamilyID=9442b0f2-7465-417a-88f3-5e7b5409e9dd