Yes, I found that out the [really not so] hard way. But WOO-HOO! the serial connection is up. Unfortunately, I cannot with any degree of surety, point to the change that made it possible.
My suspicion is that either my PC's serial port (which I added on and plugged into the appropriate port on the motherboad), or the null modem cable, was faulty.
For when I went out and picked up a USB to Serial adapter, and new null modem cable… it worked, both with Minicom, and GTKTerm.
I have what looks to be one last hurdle to overcome, but since it's a different issue, I'll start a new thread.