SOLVED! The internet and Google are my friend!
If a device is not showing up, Google told me to go to Device Manager and look for a device with a yellow exclamation point. Lo and behold, there was a device named FT232R USB UART which sounded suspiciously like what I was looking for. I am familiar with FTDI chips and USB to serial on my ham radio programming software and cable, so I knew I was on the right track.
So I Googled FT232R USB UART, and ended up at the FTDI site on their drivers download page, and downloaded the driver(s) for Windows 7.
The FTDI notes say this is a two stage driver installation, so I did the manual driver update for the FT232R USB UART device, and as FTDI said it would, that caused another device to show up in Device Manager, this one called USB SERIAL ADAPTER, also with yellow exclamation point. I repeated the manual driver install, and now there there is a device called Ports.
I finally ran Coastal Explorer's Auto Detect Ports, and it told me it found a COM port on Com 3 at 38000 baud, and automatically configured it for baud and "listener."
As soon as I did that, the info from the C-80 (location, speed and course, and it no doubt will show depth when I am in the water and have the depth sounder turned on) showed up on my PC monitor. I hit the Tracking tab, and an AIS Vessels list showed up, but there were no vessels in the list, again, I trust this will work when I am out on the water, since it knows the AIS is there. Since my boat is in the garage, Coastal Explorer shows the boat on land and keeps telling me "Land ahead" in case I didn't know! I don't know how (yet) to make CE stop talking to me!
Color me relieved and no longer frustrated. I give Digital Yachts an "F" for their driver installation CD, which simply failed, but all is well that ends well!
Thanks all!