RPC over HTTPS Troubles

I followed the steps in 'How to Deploy RPC over HTTP for the First Time on
Exchange Server 2003 SP1, No Front-End Server
'(http://www.microsoft.com/technet/prodtechnol/exchange/guid es/E2k3RPCHTTPDep/48d6d03d-64c2-470f-9561-6de9003effe4.mspx) '.
I installed and configured a Microsoft Certificate Server on the same
server. If I try to connect to the Exchange server using Outlook 2003 and
SSL, I do not get a login prompt. If I turn off SSL on the server and
Outlook client, I receive a login prompt, but that is followed up with
another error. After doing some research, it looks like Microsoft recommends
basic authentication with requires SSL. Also, when using SSL, the client
must trust the authority for the certificate. When I connect to
https://mail.company.com/exchange/ I receive an error for, 'This Security
Certificate Was Issued by a Company that You Have Not Chosen to Trust'. I
tried to follow the steps in Microsoft KB 297681 (I received a 500 internal
error) and manually import the certificate into the 'Trusted Root Certificate
Authorities' in IE, but everytime I try to access OWA, I receive the same
error. How do I get this certificate to be trusted? Should I be selecting
the 'mutually authenticate the session when connecting with SSL' check box in
the Outlook setup?

Sorry for the lengthy post...thanks in advance