Small external hard drive suggestions

Today I'm interested in a general opinion for an external hard drive.

I am using an aging MacBook Pro (2007 model) with Snow Leopard. I already have one 1TB hard drive which does its work very well, which I use for my time machine backups.

What I'm looking for is a smaller external HDD that works with a USB only connection (my current one requires power connection), small, and durable so I can carry it around. I am not planning on dropping it often, it's going to be safe in my beg.

I am going to use it to store pictures and video clips which I need to encrypt and protect. I'm looking for something easy, yet very secure. I'm familiar with True Crypt and the like, but I'd like something even smoother.

I was looking at my passport series, I'm a fan of Western Digital, and this is what I am thinking of getting, but I was wondering if you guys have other recommendations? Factors to include are:

* USB power only
* small, fit-in-your-pocket kind of thing or slightly bigger
* Around 100GB, don't need much more than that.
* durable (it will be carried in a backpack between books and such)
* no crazy colors (yes I know, but looks matters to me.. I rather have something black or aluminum than some blue plastic for example)
* price - I'd like to keep it around $100, no more.

Suggestions?

Oh, I've been using a USB flash drive so far with 5GB storage. It works, but it's too little storage and I'm worried it will die on me one day. I'm under the impression external harddrives outlast USB flash drives.