Maintain Domain and UserName – Rmte Mail

I support remote users that use dial up networking to access their e-mail from an exchange server on our network, using Outlook 2000 as their client.
When they dial-in, they are prompted everytime for their UserName, DomainName and password.
In Windows NT, I was able to edit the registry to add 2 values to the HKEY_CURRENT_USER\Software\Microsoft\Exchange key to maintain the values in the prompt. I added LogonDomain and UserName. I do not know where to enter these values in the Windows 2000registry. Can you tell me where, or tell me how to maintain the User name and domain name in the prompt that displays when dial-up networking connects to the Exchange server?