T61 with 965 graphics, external monitor is plugged in and configured as follows (using gnome-display-properties):
VGA1 connected 1024x1280+1680+0 left (normal left inverted right x axis y axis) 338mm x 270mm
LVDS1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 331mm x 207mm
The y == 0 line doesn't align with the left edge of the monitor, but instead appears about 2/3s to the right, with the top half of the image below it, and the bottom half above it.
Making matters worse is that input does not seem to have the same offset, so clicking things on the rotated screen is _extremely_ hard....
I think we could use /var/log/Xorg.0.log, so that we have some clue what Xserver thinks about.