Why don't we encrypt our USB disks and USB harddisks? Well, most people think it's difficult, so lets dive into some details encrypting your drives with Bitlocker To Go in Windows 7.

So we want to protect the data on our USB devices, so in the event that we lose a device (or when it is stolen) the information is unavailable to other people. Note however that it's still possible to format the USB drive, only the information is encrypted, but our goal is achieved, nobody can access the data.

Use FAT32 for older systems 
If we want to access our Bitlocked data from older (non Windows 7 systems), then make sure the USB drive is formatted as FAT32 !!! All drives with formatted with NTFS won't have the Bitlocker to go reader, so you'll be unable to access your content(read only)! Only with the FAT32 filesystem a seperate partition is created with the reader application installed on it. NTFS drives will prompt the user to FORMAT the drive, so watch out with this!

Getting started
Just right click your device, and choose: Turn on Bitlocker...

Enter a password, save the recovery key to another drive and now just wait.... quite some time before the complete device is encrypted. This can take up to a few hours for larger devices. For unlocking the device with a smart card, the certificate on the smartcard needs to have the right (Extended) Key Usage mentioned. See this article for more information: http://blogs.technet.com/deploymentguys/archive/2009/06/17/windows-7-and-bitlocker-cmd-line.aspx 

And for how to remove Bitlocker from a drive: http://blog.unlockforus.org/2009/05/how-to-remove-bitlocker-encryption-in.html

Just ask yourself these questions: Where are all your USB devices at this moment, did you loose some? Who has access to your devices. Did you ever forget your USB disk in the train/subway/bus/internet cafe? Did one of your coworkers lose anything lately? Any events in the news where a bank, military or government worker lost a USB drive?