While the backup conveniences are valuable, the portable flashdrives could become a security exposure. The drive's small portability factor makes it easy to lose the device and the data that resides on it. Also, as the software drivers for the flashdrives often make use of Windows 2000 and XP ?plug and play? environment, someone could insert a flashdrive into your computer and download private information from your computer.
If you use a USB flashdrive, it is important to protect the physical security of the device. Do not leave it in a location which could lead to theft or loss of the flashdrive. In respect to protecting your computer from unauthorized use of a USB flashdrive, you can configure Windows to reject any drive plugged into your USB connection, but keep in mind that such changes need to be done carefully to avoid unwanted changes and that the change will also impact your use of a USB drive. Microsoft support web pages provide guidance for configuring the Windows 2000 and XP operating system to reject USB connected drives.
It may also be possible to encrypt the data on the portable USB flashdrive. Some drive manufacturers include encryption capabilities. As an alternative, some drives may permit use of Windows Encrypted File Services (EFS) to secure the data on the flashdrive. Mac OS X includes the capability to encrypt home directories via FileVault; however, it does not appear this function can be extended to flashdrives.