Formatting the current Hard Drive in the MacBook Pro

I am about to swap hard drives between two systems and will need to install Lion onto each of them, once the hardware is swapped. And to prevent me from accidentally booting either new machine with an incorrect Lion install, I want to wipe the drives as my last action before taking the machines apart.

How do I do this?  If a new OS will be installed on restart, can this be a quick format? What options should I select for this reformat of the two drives?

Thanks.