Media Card Reader PS3: What Do I Need The Media Card Reader For?

PS3: what do I need the media card reader for? - media card reader

I intend, my 11yr old to be a PS3 and I'm looking for differences. It will only be used for games, and is also using it for movies. He has a PS2 and I'm not worried about backwards compatibility. What do I need to know is:

What are the USB ports are used?

And what is the card you use?

(In fact, if I have 40 GB, I miss these features?)

Thank you!