Western Digital is actually a well known name in the hard disk area, I was surprised to find out because I have never heard of it before. The WD external hard disks have received some press coverage recently because of their new My Passport 2TB hard disks. The ones I have purchased are the 1TB versions because it is on sale at just $99, usual price $209. It's about as much memory as my computer has so it should be enough to provide backup.
This particular My Passport version is about as big as a passport and lightweight making it ideal for travelling and transportation. It also supports USB 2.0 or 3.0 depending on the version you are using at the moment. Non-slip pads underneath so it stays in place. WD hard disks also comes with password protection, continuous updates and faster downloading times.
I am a basic user so those features are good but the reason I bought an external hard disk is to backup my computer. It is a lot faster than the days it took to copy that same data onto piles of CD/DVDs. It also has an interface that allows me to manage and select the data I need, really user-friendly.