Appreciate your guidance, VERY much.
I used your template to rework the zone file in place of the Mandriva one.
In summary, it now looks like this (with dscdirectionalservices abbreviated to dsc)
dsc.com. IN NS ns1.dsc.com.
ns1.dsc.com. IN NS 192.168.1.65
dsc.com. IN A 192.168.1.65
mail.dsc.com. IN A 192.168.1.65
dsc.com. IN MX 5 mail.dsc.com.
www.dsc.com. IN CMAME dsc.com.
dig shows the MX record pointing to www.dscdirectionalservices.com on the internet.
email is now working.
Only the 1 nic card runs from the 2WIRE gateway.
/etc/hosts still shows 127.0.0.1 localhost.localdomain localhost and 192.168.1.65 www.dscdirectionalservices.com www
sendmail parsing is also running: ie my email address shows as gjwalsh@dscdirectionalservices.com.
My concern is with the 192.168.1.65.
This is the IP masquerading via the 2WIRE of our public static IP address. It won't change, of course, but I am concerned about the 192.168.1.65 changing without my being aware and bringing the system down.
In the past, I had control of /etc/resolv.conf and ran everything with 2 nic cards, one to the internet and the other the local lan which provide the ns1 and mx functionality. Now, 2WIRE overwites it.
Maybe this is okay .. I'm just a little nervous about it. Seems shaky to me although it DOES work, thanks to your help in cleaning out the cobwebs of confusion in my head.