Toshiba's NB-100 netbook comes with the Windows XP operating system; this includes a CD for reinstalling, reformatting and other troubleshooting options. The problem is that the small laptop does not include a CD or DVD drive. In order to reformat the hard drive, you must have an external CD/DVD-ROM drive to access the Windows CD. This requires erasing the hard drive and reinstalling Windows, so back up your data beforehand.
Connect an external CD/DVD-ROM drive to the Toshiba netbook via USB cable. Plug one end of the USB cable into the external CD/DVD-ROM drive; plug the remaining end into a free USB port on the Toshiba NB100.
Place the included Windows XP CD into the external disc drive. Restart the computer to boot from the CD.
Press "Enter" at the welcome screen to enter the Windows XP Setup. The welcome screen appears when you've properly loaded the XP CD, introducing you to the Windows XP Installer. Press "F8" after reading the license agreement to accept the terms.
Select the current Windows partition (labelled "C:" and/or "Windows") from the displayed list of connected drives, when prompted to choose an installation destination. Use the arrow keys. In many cases, the Windows partition is the only option. Press "D" to delete the partition and confirm the action. This erases the Toshiba's hard drive.
Press "C" to create a new partition, using the NTFS file system. This automatically reformats the hard drive and takes only a minute to complete. Select this new partition as the installation destination.
Follow any remaining prompts to complete the install of Windows XP. You may be asked to enter your Windows product key, name the computer and configure an administrator account. A progress bar displays the remaining time of the XP install; it may take up to an hour. When finished, the Toshiba reboots and launches a brand new copy of Windows XP on your reformatted hard drive.