How to Clear a Computer Reinstall a Windows Operating System

Installing Windows XP
1. Insert your Windows installation disc into your computer and restart the machine. As the computer boots up, press the boot menu key, which is displayed on the splash screen as the computer first starts up. This key is usually the 'Delete,' 'F1,' 'F11' or 'F12' key.
2. Press the 'Enter' key at the welcome screen and then press 'F8' to agree to the license terms and conditions.
3. Choose the hard drive you wish to install the operating system to and then press the 'D' key to erase the data on that drive. Press the 'Enter' key to choose to install the operating system to that drive. The installation process then starts.
4. Enter the CD key for your operating system when prompted. This alphanumeric code is listed on the sleeve or packaging of your Windows installation disc. Wait for the installation process to finish and then you can use your computer.
Installing Windows Vista or Windows 7
5. Insert your Windows installation disc into your computer and restart the machine. As the computer boots up, press the boot menu key, which is displayed on the splash screen as the computer first starts up. This key is usually the 'Delete,' 'F1,' 'F11' or 'F12' key.
6. Choose the 'Install' button when you see the welcome window appear. Agree to the license terms, press the 'Next' button and then click on the drive onto which you wish to install the operating system.
7. Choose the 'Delete' option to erase the data from that drive and then click on it again to select it as the installation drive.
8. Enter your product key when prompted and then wait for the installation process to finish. This alphanumeric code is listed on the sleeve or packaging of your Windows installation disc. When it has finished, you can log in to your computer.