If you’ve ever had to reinstall OS X, chances are you’ve used the Apple-provided system installer disc that came with the Mac. But what do you do if you misplace the DVD, or it becomes unreadable, or worse—your SuperDrive isn’t working? Having a backup of your system installer disc could save your bacon.

A secure operating system that can be carried around on a flash drive will be unveiled at the Infosecurity conference in London later this month.

Trusted Client is an encrypted operating system that its maker, BeCrypt, claims will "provide a trusted environment on an untrusted host". According to chief executive David Holman, the system has "already been piloted at a major UK government site".

You can have now have a full-featured Linux OS booted from a USB stick or thumb drive. Linux distributor Mandriva's Flash 4GB provides Mandriva Linux 2007 KDE 32-bit, which needs no installation-- being ready to boot off the USB 2.0 stick. Plug in the stick, turn on the PC, and Mandriva Linux is ready to use in a few seconds.

It includes drivers for common PC video cards, wireless adapters and modems-- as well as the required firmware. It also offers some open source desktop environments, applications and plugins:

- KDE 3.5.4 (GUI- desktop environment)