How do I get user information from MS Exchange

I am developing a ASP/Intranet help-desk application.  I would like to pull information directly from the MS Exchange database of current system users.

I have seen code from various web sites but do not understand all of the requirements.  I also do not know exactly which servers the code page must reside to retrieve the information (exchange object).

I have tried the code below to determine the current user logged to a workstation, and then retrieve and object from MS Exchange with user information.

 'get the user logon name
 authUser = Request.ServerVariables("AUTH_USER")
 'the server variable will be in the following format: DOMAIN\logon
 'so we have to remove the MCDOMAIN1\ part
 logonName = Right(authUser, Len(authUser) - 10)
 
 'get the user's object
 Set user = GetObject("WinNT://ABCXYZ.org/" & logonName)

The code above worked on another system, I was associated with.  Are there any sources on this topic, or do you have a specific code solution?

Technical Info.  Windows NT 4.0 & 5.0, Client for MS Networks, MS Exchange (TCP-IP), User Mail serviced by Outlook 98/2000.  System is fire-walled.