You can never have too much digital storage, and the day will comesooner than you thinkwhen you wont be able to squeeze a single new file onto your computers hard drive. And if your primary computer is a laptop or an all-in-one desktop, you wont be able to solve the problem by opening the case and tossing in a supplemental drive. One solution might be to rent storage space in the cloud, but buying a hard-drives worth of capacity is prohibitively expensive: 500GB of storage on Dropbox, for example, will set you back $499 per year. If you need just storage, as opposed to a service for file syncing or collaborating via the cloud, buying a portable hard drive is far more economical. For less than $200, you can get a 2TB drive that supplies four times the capacity of a Dropbox account.