Upgrading HHD on a NAND phat system?

So I recently upgraded my phat system to a CFW Evilnat. But I only have a 120gb hard drive as of right now. If I am correct to my understanding, do all I have to do is put the new hard drive into the system and just reinstall all my games since the firmware is written to the nand? Or do I have to reinstall my CFW again?