- Trying out Linux before committing to use it
- Running a Linux install in a user friendly way
- Using Linux tools to fix a machine or rescue data
- Using a machine without changing any data on it
To use a Live-CD the PC must be able to boot the operating system from a cd-rom rather than the hard drive. When a PC is switched on a small piece of software in the mother-board (the BIOS) decides where to load the operating system from (typically the hard drive). On most PCs its possible for the Operating system to be loaded from any storage device, such as the floppy disk, the hard drive, CD-ROM , DVD-ROM or even a memory stick. If the machine looks for the operating system on the internal hard drive before looking at the CD-ROM, then the Linux live-cd does not get a chance to load. To fix this you will need to change the boot sequence in the BIOS settings. The BIOS settings can usually be accessed by pressing F2 when the machine is starting up (it may be another key, in which case look at the manual for the machine).
With some Linux distributions its even possible to boot the operating system from a memory stick. This means that you can have your own operating system and documents on a usb stick and take your computer around with you. If I try this I'll blog about it here.
However its worth noting that not everything always works, this was my Experience: Laptops have not been a great success. My Acer laptop can't boot from a CD since I've lost the BIOS admin password (set in an attempt to teenager proof the machine) and can't change the settings (my fault and very stupid on my part). The Fujitsu Amilo 2010 laptop will not run the Linux Windowing environment because the Graphics chip is not compatible with the standard Ubuntu Live-CD. The 128MB old machine has not enough memory to allow the Ubuntu Linux Windowing environment to start. However my son's PC worked fine first time and the old 128MB PC booted into DamnSmallLinux Live-CD without problems.