ATLANTA - Flash memory drives, the size of your thumb, are dirt cheap and offer gigabytes of storage. It's tempting to fill one of them with important computer files, clip it to a key chain and hit the road.

But what if you lose it while fumbling for change at Starbucks and the hacker in the corner finds it? This is not a good thing.

That's where a new breed of flash drives comes in - chock full of military-strength encryption and passwords and keypad combinations that must be entered before the data can be accessed.

I put a few secure flash drive solutions to the test: Take Anywhere's Pocket Safe ($59.95), the IronKey ($149) and TrueCrypt, a free software program that works with any USB flash drive.

Each had its strengths and limitations, but I liked the IronKey unit best, with its built-in Firefox browser, large storage space and powerful password protections.

Setting up my 4-gigabyte, brushed-metal IronKey drive was pretty painless. After putting it in a USB slot on my home PC, I was asked to create a user name and password before I could access any of the storage space or other features. (Among those extra features: You can create an encrypted backup of the IronKey's contents on a PC desktop.)

Then, every time you plug the IronKey into a computer, a control panel appears on the screen to ask for the password again. No password, no reading or tinkering with the drive's contents. In fact, you have to be careful, because if you enter the wrong password 10 times in a row the unit permanently deletes all of your data and is no longer usable. You can't even reformat it. That's tough love.

My favorite IronKey feature was the built-in Firefox browser. It let me take my favorite Web bookmarks and login information with me, along with my Web surfing cookies and site history. This means I left no trace of my Web browsing on the computers I plugged the IronKey into.

The IronKey works best with Windows XP, Linux and Mac OS X, according to the company.

Next up was the Pocket Safe (for Windows only), from Take Anywhere. The 1-gigabyte device sports a numerical keypad on its case. If you don't remember the password you create, you won't be able to launch the drive's software control panel.

I picked a four-digit password, but there are two numbers for each of the five entry buttons on the keypad. So if my access code were 1-2-3-4, someone could guess it by keying in 0-3-2-5 or 1-2-2-4 or other shared-button combinations. This was disappointing.

Once I keyed in my correct password, a green light began to blink, telling me it was safe to insert the Pocket Safe drive into my USB port.