I have the Silverlight 2009 package and I recently updated it with 2009.1 526, the newest version available in my downloads. The "What's new" file clearly states that it supports Silverlight 3 and DomainDataSource...to me, this is the same as saying it supports RIA because that's what you use DomainDataSource for in Silverlight 3. Apparently, this isn't the case because my projects build but the browser crashes. However, if I switch the DLL's with the new DLL's from the sample code of the latest version (I have not upgraded to this one yet) the projects run just fine. Does this mean I have to buy the new Silverlight package just to use RIA?