Hi Neal & Just18!
Guess what? SOLVED! Finally!

Just18 you are quite correct, there are 3 S3 packages to uninstall and Neal I checked for any DKMS packages (checked ALL of them listed in Synaptic actually) but there was only one for NVidia and two other generic ones, nothing for Unichrome. BUT... it made me have a look in the X11 folder for any packages that might give a clue... nothing. But I did open up xorg.conf file for what it's worth... and there it was!
DRIVER: "OPENCHROME"! What is this? Oh it's only the
Linux Openchrome Project for Via Unichrome chipsets!!! Gotcha! Uninstalled that as user AND root... problem solved!
Wow! After all this time and 800 odd views by others there are some lessons to be learned here which may help others:
1) Removing a video driver as a user
DOES NOT REMOVE IT IN THE ROOT DIRECTORY and has to be done
in root. Although I can see the logic of this if you were running a network, not really appropriate in a stand-alone desktop. Perhaps there should be two variations: Linux-DT & Linux-NT.
2) Removing ANY video driver also removes Task-X11. Going into PCC > Configure VGA to change a driver requires Task-X11 to do that task and will download it automatically before the usual options window comes up. Downloading Task-X11
ALSO PULLS IN ALL OTHER VIDEO DRIVERS AS WELL BRINGING YOU BACK TO SQUARE ONE! Now I think that's wrong and is a real pain in the a*** and should be changed, because that's taking control/choice away from the user.
3) This must be a common problem therefore with anyone with disabled on-board VGA and somewhat surprised this hasn't been an major issue before I came along.
So there we are. As I type this I'm working off the LiveUSB now... proof it's all up & running; so all I've got to do that's left is to make the relative changes on the host system, produce an updated iso file, burn that to a CD, and if that's successful (and I have no doubts on that), then I can well & truly mark this thread as "solved".

Thanks to Neal for the tip... just
that thought pattern to give a moments inspiration (90% perspiration!), and for Just18 who kept by my side in my weaker moments of giving up!
All the very best to all of you
