Concerned about people accessing your private information whenever you use a public computer? Worry no more. There are new devices available that are small as a key chain that allow you to use any computer without leaving a trail of evidence.

According to Reuters, a new computer program known as MojoPac can turn most flash memory sticks, hard drives or iPods into “virtual” PCs that can run most programs that work on Windows XP.

The devices function by drawing on the host computer’s resources, including its electricity, Windows XP software and DVD drive.  However, the devices retain their independence as they move from machine to machine, allowing people to use public computers without a trace of their session being left behind, Reuters said.

The new devices cannot be purchased at a store; you have to make it by downloading free software onto a computer driver such as the thumb-sized USB flash memory drives. You can also use iPods, and many other digital music players and regular external hard drives, according to Reuters. 

Once the MojoPac “shell” is created, users need to install their own software - just as they would do on a regular PC running Windows XP.

“It’s a slick way to move from machine to machine,” says Rob Enderle, founder of the Enderle Group, a research firm that follows the PC industry. “It’s about as safe as you can get.”

Other companies are working on similar technology, but there’s nothing available with free software that is as easy to set up as MojoPac, according to Enderle.

MojoPac virtual PCs can also protect users who share the same computer. For example, a virus introduced by one user into their “virtual computer,” would not affect the rest; meaning, if you corrupt your virtual PC, your main computer would be fine, Reuters said.

For now MojoPac only works with Windows XP, but the company plans to launch a version this summer that allows users to switch between machines running XP and Vista, according to Reuters.