Newbie - Trying to AS PC2003 with SBS 2003 Exchange

Hi

Please forgive my lack of knowledge.
I'm using AS 3.8
My SBS 2003 server has exchange 2003 with sp2 and is configured like this.

hit.local is the internal domain dns name
mail.hit.net.au is the name of the exchange server and is the name we used
in the CEIC Wizard
Our isp points our email to mail.hit.net.au
Originally when we installed the SBS the CEIC Wizard used www.hit.net.au as
the web server name but we changed it to mail.hit.net.au because the www
name is hosted at the isp.
We tried exporting the certificate and then importing it to the pc2003
device.
This would not let us sync with exchange.
Then we got a certificate from startcom.org and installed that on IIS and
re-ran the CEIC Wizard
Then we exported the certificate and imported it into the pc2003 device.
Still no joy with syncing to exchange.
I have read many articles on certificates and the truth is that I'm now even
more confused than ever.
Can someone explain in words I'll understand exactly what I've got to do to
get the device to talk to exchange through AS.

Thanks in advance
Mike Hatfield