public class LocalizedStrings
{
   public LocalizedStrings()
   {
   }

   private static SilverlightApp.Resource1 resource1 = new SilverlightApp.Resource1();

   public SilverlightApp.Resource1 Resource1 { get { return resource1; } }
}

<TextBlock Text="{Binding Path=Resource1.HelloText, Source={StaticResource LocalizedStrings }}"/>