Procedure for Dell Inspiron 300m and Toshiba Satellite, Other systems may be similar.

Insert Dell supplied "Operating System" cdom into cdrom drive. Dell provided this cdrom when you purchased your system.
Restart your computer

 

Sony, Insert cdrom labeled "sony system recovery cd"

Restart your system

 

Toshiba: Repeatedly press lower case character c as system boots, system should boot from Toshiba cdrom xp operating system disk.

Dell: Look carefully at lower left of your screen, you should see F2:Setup,F12: Boot menu

Dell: Press F12

Dell: The Boot menu lists the disks, network boards and cdrom drives installed on your pc. They will vary between different Dell models.

Here's what a boot menu looks like, yours might be different.
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Boot Menu

IDE HDD - fujitsu mht2060Ah
usb cd: _NEC DVD+RW ND-5100A-
PCI Lan: ONboard Nic
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Chose the one that looks like a cdrom drive. If you chose the incorret one, no damage is done. The system boots back to a blue screen.
Use the arrow keys and select your cdrom drive, Dell's 300m cdrom drive is USB cd:. Once selected press the <Enter> key.

The system displays:
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Press any key to boot from cd

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Hit any key.

Start the recovery console