If you already have Visual Studio 2010 installed (or the
free Visual Web
Developer 2010 Express), then you can install both the Silverlight 4
Tooling Support as well as WCF RIA Services support by downloading and running this setup package (note: please
make sure to uninstall the preview release of the Silverlight 4 Tools for VS
2010 if you have previously installed that).
The Silverlight 4 Tools for VS 2010 package extends the
Silverlight support built into Visual Studio 2010 and enables support for
Silverlight 4 applications as well. It also installs WCF RIA Services
application templates and libraries:
Today’s release includes the English edition of the
Silverlight 4 Tooling – localized versions will be available next month for
other Visual Studio languages as well.