Sincere thanks for your help, mate, especially that you came back to give a bit of simpler advice.
I tried to run through the ArchLinux solution late last night, and kept a log of all the files I had to apt-get and otherwise download a tar.gz and configure-make-make install, and got lost somewhere in pixman with my pkg-config globals, and hence gave up and tried Ubuntu 12.04 to no avail. sudo ldconfig wasn't good enough at that point.
I have now redone the logical paritions on the ASUS to allow me to test out four differens OSs at once, while doing the research here on my old trusty Compaq CQ-60 which does still work okay on the old Karmic Koala, and I'm starting with a fresh install of Mint 12 now, and have 20 minutes to go until install complete.
Looking through the /etc/X11/ directory, I haven't found any xorg.conf file on the Live USB, but will wait until the install is complete and see if it might show up then.
I'll edit this post when the latest install is complete.
I'm afraid I'm still unable to find any /etc/X11/xorg.conf file in the new Mint 12 install, and have been checking through as many files as I can including /usr/share/X11 and usr/lib/X11 but without much luck on a Saturday night, so ...
I'm going to reinstall Mint 11 Katya (which has a much more easily adjustable panel) and see if that will let me do the change to the xorg.conf file.
Thanks again for your help, and I might try the ArchLinux method again if this doesn't work, because there may have been some version conflicts along the way when I might have downloaded the source for a file that was a newer version, rather than get it from the usual apt-get means. It took long enough last night that I wasn't about to try again at the time.
I can see this getting sorted before the weekend is over, but thank you for pointing me in what appears to be the right direction. Wish my girlfriend would buy me a new netbook oneday and set it up for me ...