How do you get more gigabytes on PS3?

You can buy and install any SATA notebook (2.5″) hard drive (hd), 5400rpm or 7400rpm and install in buy taking of the rear of the PS3. IMPORTANT- This will invalidate the warenty and it is also a goosd idea to back up for hard drive before hand. It is also possible to connect external hard drives but i am not sure how