Silverlight 4 & WCF: Windows authentication continues to emerge

we developed the SL4 application with the WCF service. The SL application and service are hosted in IIS 7 with Windows Authentication enabled, and everything else is disabled. In wwroot, I have this client access policy file:

<?xml version="1.0" encoding="utf-8"?>
<access-policy>
 <cross-domain-access>
<policy>
  <allow-from http-request-headers="*">
    <domain uri="*"/>
  </allow-from>
  <grant-to>
    <resource path="/" include-subpaths="true"/>
  </grant-to>
</policy>

and this crossdomain file:

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
 <allow-http-request-headers-from domain="*" headers="*"/>
</cross-domain-policy>

the silverlight xap service configuration looks like this in the client section:

 <binding name="SilverlightEndpoint" maxBufferSize="2147483647"
        maxReceivedMessageSize="2147483647">
      <security mode="TransportCredentialOnly" />
    </binding>
    ....
    <client>
  <endpoint address="http://app.domain.intern/MyService/MyService.svc"
      binding="basicHttpBinding" bindingConfiguration="SilverlightEndpoint"
      contract="[interface]" name="SilverlightEndpoint" />
     </client>

, Internet Explorer, Windows, . , , . , , : "http://[_]/MyService/MyService.svc". - , ?