Hello,
My screensaver works fine as does the energy saver options on my iBook 700 14.1". Have you tried testing the screensaver or tried using hot corners? This might at least tell you if you have a problem with your screensaver files. Other than that, I cannot advise you any further.
I have my settings all my energy saver settings turned off as I primarily use my computer when its on external power.
Good luck!
James