Enumerating users on remote machine without logon   

How can i  Enumerate users on remote machine without logon?
I am calling dwResult = NetQueryDisplayInformation ((LPCWSTR)pWideServer, 1,
nIndex, 10, 24, &dwCount, &m_pBuffer) but it is returning
ERROR_ACCESS_DENIED. is it necessary to connect to the remote machine first?
Thanks

date: Mon, 12 Mar 2007 16:46:02 -0800   author:   shoeb