Lists listService = new Lists();

NetworkCredential credentials = new NetworkCredential();
credentials.UserName = serviceUserName
credentials.Password = servicePassword;
credentials.Domain = domain;

listService.Credentials = credentials;
listService.Url = serviceUrl.ToString();
XmlDocument xmlDoc = new XmlDocument();
XmlNode nodeListItems = listService.GetListItems(categoryListName.ToString(), null, null, null, "10000", null, null);