I have been developing my program on my Intel macbook ( graphics card GMA
950) and was looking forward to working on my G5 , but Processing 1.0.5 says

You need to use "Import Library to add processing.opngl.PGraphicsOpenGL to
your sketch"

if I try one line

size(100,100,OPENGL);

the graphics card on my G5 is ATY,RV351

Hm, not sure what would be wrong, though it may just be a problem with the
setup on that machine. Is it possible you have conflicting versions of JOGL
installed? (e.g. jogl.jar anywhere else on your machine). Also try changing
your sketchbook folder to an empty folder, and then restarting. Sometimes a
conflicting library can break OpenGL.

I had to remove the Libraries folder from my Sketchbook folder. I put all
the libraries that were there into the Processing package ( Contents /
Resources / Java / Libraries ) and it works on my PPC.

Maybe thats documented somewhere? sorry if it is.

right, so that's a bad library. all you've done by moving those libraries
is changed the order in which they're loaded. stick with my original
instructions to change your sketchbook folder to something empty, and it
should work as well. don't install libraries with the built-in versions,
that may no longer work in the future.