An image from a high end digital camera can exceed five megabytes. Recorded TV and (legally) stored movies approach 10 gigabytes. Transporting files via email is often not an option because of size or sensitivity of material. Server uploading and downloading is an option, but can be slow -- especially if you are wireless. Burning to DVD or CD can work -- or it can lead to the "DVD as Still Life" syndrome -- where an office is salt-and-peppered with hundreds of unlabeled DVD's and CD's. You need a large, portable, rewritable, rugged option.