While using your awesome Apple machine you might need to know that is your mac OS X 32 or 64 bit ?
You may need this info for some software that you want to install on your computer to confirm it’s compatibility or just out of curiosity too!
So quick answer is:
Mac OS X 10.5 and above (which means Leopard (10.5) and Snow Leopard (10.6) and any upcoming models hopefully) are all 64 bit operating systems.
All currently being shipped mac’s have a 64 bit processor (intel) and 64 bit operating system.