go into the Bios, turn your "AI Tweeker" to manual and set the FSB to your desired O/C settings. look in the "how to Guide" on toms, to get the formula's on what number to actually enter in the FSB to get the GHz you desire. Click your "ram frequences" and set the freq to manual set then sellect your ram speed to DDR2 800MHz.
leave everything else on AUTO that will get you by till you learn how to use all the settings and you can refine your Overclock.
Go to the ASUS website and download the Manual for your Motherboard and it will tell you what all the Settings are and what they are used for in your BIOS.
I dont have a P5QLD Pro, but i do have a P5Q Turbo. Im sure they run the same Bios program. I hope it does because what i told you is based on what i assume your bios is.