So I went into the Forum Chat and got a couple suggestions, which I thought I would document here for those coming in the future.
On the MD, when it popped up the "Can't start X" message window (and just stuck there) I pressed CTRL-ALT-F2 and logged into the terminal as root with no password.
I was trying to follow the instructions provided in a previous reply of this thread, relating to installing the via xorg drivers, and it failed, as noted in one of my previous messages.
It was suggested to add some lines to the /etc/apt/sources.list file under /usr/pluto/diskless/109 on the core (where 109 is the device number of the MD as shown in the web admin screen).
So, on the core, I edited:
/usr/pluto/diskless/109/etc/apt/sources.list
and I added at the very top:
deb-src
http://archive.ubuntu.com/ubuntu/ gutsy main restricted multiverse universe
deb-src
http://archive.ubuntu.com/ubuntu/ gutsy-security main restricted multiverse universe
deb-src
http://archive.ubuntu.com/ubuntu/ gutsy-updates main restricted multiverse universe
and then issued a:
sudo apt-get update.
From there I was able to issue the commands to grab the xserver-xorg-video-via stuff as instructed in the link given earlier.
One oddball thing, of course, is after issuing a reboot and watching it boot off the network again, I still got "Unable to Start X". When I went and looked at /etc/X11 (on the MD) there was no xorg.conf file, but there was some old backup, so I copied it over, edited the file as instructed, though, wahoo, and tried again. Still no go.
I then tried:
sudo dpkg-reconfigure xserver-xorg
and walked through all that techno mumbo jumbo. It recognized the via video OK
I was able to get X to load on the command line afterwards (with no windows manager).
That's pretty well all I can do.
(after edit, close to 11pm)
My other PVR-150-MCE arrived today and I installed it in my AMD MD box and now it too won't boot up over the LAN, stuck on loading firmware in the IVTV area, and it completely whacks my network and disables all traffic until I power it off.
I think it's time to say thanks, but no thanks. 7 full days of banging of my head up against the wall and every time I turn around there is something wonky screwing up the system.
Tomorrow I think I will wipe my drive clean of LinuxMCE and give MythBuntu a try. Surely it can't be as rocky as LinuxMCE. Maybe in another year (or two) LinuxMCE will be more mature and I will revisit it, but it's time to get back to my life.