Hold 6 and 4 when you're booting. Most machines that have the ability to boot 64bit are not doing so by default. There is a terminal command you can find somewhere that will set the default for you.
MacBook models (at least pre-the most current white unibody, not sure if it can) cannot boot in to 64-bit mode. You won't see any performance difference as Applications can still run in the 64-bit space.
MacBook models (at least pre-the most current white unibody, not sure if it can) cannot boot in to 64-bit mode. You won't see any performance difference as Applications can still run in the 64-bit space.