Big cases make for a tighter fit on your desk, but you can put more in them. As soon as you turn the computer off, the information stored in RAM goes away. For permanent information storage, your computer will use a magnetic media very much like audio tape. The slots found on the front of most computers give you access to the first kind of disk drive. The density of a floppy determines how much information you can actually store on it.
Hard disks provide much more data storage than a floppy.
1000MB becomes 1GB, one gigabyte. Gigabyte hard drives, once unthinkably large and expensive, are now standard equipment. Well, think of the most storage you could ever possibly want. Remember, we're talking about millions of bytes here. Okay, now double it.