This is a register issure

I know for the free this will work

HKEY_CURRENT_USER\Software\Google\SketchUp8
save the old sketchup 8 register key and make 2 copy

delete old sketchup 8 reg register

now
reinstall new sketchup 8 to differnt location
move a copy of plugins to new sketchup 8
now it should work for the new and old

edit old reg to tranfer back setup infor you want to bring forward to new register.

once in a wild copy plug-ins back to old to keep toolbars link

Thanks again for the suggestion, but as you say, the background image doesn't lne up so well.

In the meantime I'll continue to create another plane with the photo match image on. I've streamlined this a bit in terms of perspective by copying a face of the back of the camera object to use as the plane for that image as it lines up in 3D space exactly except for size and distance.