MS CRM 2011 AD web service authentication using Soap issue

Hi,
May i know how do we authenticate to MS CRM 2011 web services?

I am using Lotus script to do the web services which is similar to VB script language.
I was using the 2007 end point URL and now i want to switch to the 2011 web services (XRM Services).


WebServiceURL = CRMURL+"/XRMServices/2011/Organization.svc/web"

SOAPAction = "http://schemas.microsoft.com/xrm/2011/Contracts/Services/IOrganizationService/Execute"

Set objXMLHTTP = CreateObject("MSXML2.ServerXMLHTTP.6.0")
Call objXMLHTTP.open ("POST", WebServiceURL , False,UserName,Password)
Call objXMLHTTP.setRequestHeader("Content-Type", "text/xml; charset=utf-8" )
Call objXMLHTTP.setRequestHeader("SOAPAction", SOAPAction)
call objXMLHTTP.send(WebServiceRequest)

The above code is used to authenticate with the 2007 end point URL and is working fine, But it is not working for the 2011 URL.

I am getting the Authentication failed Response as shown below when i tried the 'WhoAmI' request

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"><s:Body><s:Fault><faultcode xmlns:a="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-

1.0.xsd">a:FailedAuthentication</faultcode><faultstring xml:lang="en-US">Access is denied.</faultstring></s:Fault></s:Body></s:Envelope>

I guess the username and Password should set in some other way for crm 2011?
Can anyone help me?

Thanks
Prasanth