WebService SharePoint

Hola mi Problema es el siguiente, necesito conectarme al active directory
para extraer información de usuarios, pero lo estoy tratando de hacer con un
webservice que le apunte al userprofileservice.asmx en sharepoint, pero
cuando lo llamo desde visual studio me saca el siguiente error

The document at the url http://localhost/_vti_bin/userprofileservice.asmx
was not recognized as a known document type.
The error message from each known type may help you fix the problem:
- Report from 'DISCO Document' is 'Root element is missing.'.
- Report from 'http://localhost/_vti_bin/userprofileservice.asmx' is 'The
document format is not recognized (the content type is 'text/html;
- Report from 'WSDL Document' is 'The document format is not recognized (the
content type is 'text/html; charset=utf-8').'.
- Report from 'XML Schema' is 'The document format is not recognized (the
content type is 'text/html; charset=utf-8').'.

Estoy usando MOSS 2007 y visual studio 2005 y 2008 y con ninguno funciona

Gracias por su colaboracion