newbie needs help with overclocking

Here is my set up
intel 6600 2.4ghz
2 sticks 1gb conair cm2x1024 8500cd5 set in dual channel
asus 5pb dexlue mobo bios 1004
conair 650watt psu

I ran cpu-z
the setting came up as:
voltage 2.6
core speed flipping between 1600 & 2400
fsb 266.7
bus speed 1066

the memory tab only shows one reading of 2048mbytes

the spd tab is showing
pc6400 (400mhz) max speed

the two colums give me

first colum 270mhz 4-4-4-13

the second is 400 5-5-5-18

I thought they came out of the box at 5-5-5-15??

What do I need to do in the bios (or anywhere else for that matter) to get the speeds up to at least break the bottle neck?

And why on cpu-z am i not getting all of the info on the memory tab?