If you have purchased a single name SSL certificate from GoDaddy, then I would look at whether you can return it and get a SAN/UC certificate instead, as that is what Exchange 2007 is designed to use.
I have a full walk through for the installation of the certificate request and install process on my blog here:
http://blog.sembee.co.uk/archive/2008/05/30/78.aspxOtherwise, to use a single name SSL certificate you have to make lots of changes, which is what my article above on amset.info explains, plus your external DNS provider has to support SRV records, which many do not.
Simon.