Insert your computers install disc, press C after the bong, go to disc utility, select your harddrive and erase the partition, then after that proceed to install the OS, all your data will then be gone.
Select the drive and click 'customize'. I'm guessing that you were afraid you'd click the wrong thing. That's cool.
So you gonna get another model? 15"?
Snow Leopard got a new button and instead of 'options' like the link you posted off Apple's site it says 'customize' now. It even has a blue hue to it to attract your attention to it.