This is what i use

 <configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="Redirect to WWW" stopProcessing="true">
          <match url=".*" />
          <conditions>
            <add input="{HTTP_HOST}" pattern="^your.domain.name$" />
          </conditions>
          <action type="Redirect" url="http://www.your.domain.name/{R:0}" redirectType="Permanent" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

 Yes, an other suffering Greek that is ...

 Not sure about what you ask, maybe some more knowledgable that me can help !!