If you try to install RIA(Rich Internet Application), you need to have either Visual Studio or Visual Web Developer installed on your machine. Hosting servers do not generally have Visual Studio installed and this may cause a blocker for them.
Fortunately, RIAServices.msi supports a command line parameter called “Server” which will tell the installer not to check for existing Visual Studio installation. All it needs is the .NET Framework installed in that machine.
Steps to install RIA without Visual Studio:
This will also install the RIA Services assemblies in the GAC. To learn more on RIA Services Deployment, please click here.
You may run into similar blocking situation when installing Silverlight Developer Runtime without the Visual Studio. To work around, you can install Silverlight Developer Runtime directly from here.