OK, tried again...
One thing first, slightly off-thread: on this machine, with a replacement USB CD drive which throws up none of the error messages generated during boot that the old drive caused, I can still only run the Frugal install successfully under a particular set of circumstances:
1) If the DOM is NTFS formatted, the install will fail, even if I opt to format to ext4
2) If I format the DOM to ext4 with gparted from a live install, the install will fail if I choose the 'Use existing file system' option in the installer
3) The install will only succeed (or appear to succeed) if the DOM is already ext4 formatted, AND I choose to format to ext4 during the installation process.
Maybe I'm doing something wrong, but the hardware always works perfectly with XPe, both during installation and use.
Anyway, back to Xorg. I tried 7.5 with 3d, exited to prompt, 'startx', and got a similar message to the one I mentioned above about 'ERROR: Could not map MMIO area' and 'ERROR: SiSMapMem() failed'. It also said, 'Fatal server error: AddScreen/ScreenInit failed for driver 0'
Other error messages listed included: '(EE) Failed to load module "via" (no error, 0)', and the same again for the module "openchrome"
Below those two lines it said, '(++) Using config file: "/root/xorg.conf.new"'
It's late now, but I can post screenshots tomorrow to show all the details. Once this problem has occurred, however, I am no longer able to run a live install - it too fails to the 'tc@box' prompt. In order to get a usable TC, with my limited command line knowledge, I have to reinstall XPe, and then reinstall TC without Xorg. I tried the suggestions above again ('echo Xvesa', etc), and they failed again, so I can't seem to get at the log, unles someone can tell me how to do it via the command line some other way.
Cheers, Jon.