Broadly speaking, there are two types of people who need a portable hard drive. One type just needs a little additional storage periodically and would rather have something flexible and portable than a big honking drive that plugs into the wall. The other is the high-falutin' "professional on the go" who is taking pictures, recording video, and producing tremendous amounts of data while travelling so they carry a hard drive with them every single day. While the former has their pick of any of the drives available when you search "portable hard drive" on Amazon, the latter might prefer something a little more robust -- like Western Digital's new My Passport Wireless Pro.