1. Click the 'Start' button in the lower left corner of the Windows desktop. Highlight 'All Programs' with your cursor, then highlight 'Accessories' in the menu.
2. Right-click on 'Command Prompt' in the 'Accessories' menu. Click 'Run as Administrator' and select 'Yes' in the dialog window that appears.

3. Type 'slmgr.vbs' on the first line of the black 'Command Prompt' window. Verify that you have typed the command correctly and tap the 'Enter' key on your keyboard. The command will run and the 'Command Prompt' window will close.
4. Restart your computer and allow the desktop to load. Load the Windows Vista CD into your computer and click 'Install Now' in the 'Install Windows' screen. Choose to download Windows updates in the 'Get Important Updates' screen.
5. Type the Vista CD key into the empty boxes to continue with the installation. If Windows Vista was installed on your system when you purchased it, the Vista key can be found on a sticker on your computer. If you purchased Vista separately, the key can be found on the case that contained the Vista installation CD.
6. Click 'I accept the license terms' after reading Microsoft's terms for installing the operating system. Choose 'Custom' as the installation type and select where you want Vista to be installed. Click 'Next' and the installation will begin. You should not see error code 0x80070005 again.