Accessing special folders from Silverlight OutOfBrowser application
var folder = Environment.GetFolderPath(Environment.SpecialFolder.Templates);

System.Security.SecurityException was unhandled by user code
  Message=File operation not permitted. Access to path '' is denied.
  StackTrace:
       at System.IO.FileSecurityState.EnsureState()
       at System.Environment.InternalGetFolderPath(SpecialFolder folder, SpecialFolderOption option, Boolean checkHost)
       at System.Environment.GetFolderPath(SpecialFolder folder)

using (dynamic fso = AutomationFactory.CreateObject("Scripting.FileSystemObject"))
{
    dynamic file = fso.CreateTextFile(@"C:tmp.txt");
    file.WriteLine(@"I just wrote to c: !!");
    file.Close();
}