1. Check and see if your BIOS is set up to boot from the CD drive. Do this by turning on your computer and looking for the message that says 'Press __ to enter setup' (where '__' is the key to press to enter setup; each computer is different). Press that key, and when you enter BIOS, look for the words 'Boot order' and make sure 'CD Drive' (or DVD depending on what kind of drive you have) is at the top of the list. Then exit your BIOS, saving the changes you made.
2. Insert your Windows XP CD into the disc drive and turn the computer on. When the message 'Press any key to boot from the CD' appears, press any key on the keyboard. At the welcome screen for Windows XP setup, press the 'Enter' key.

3. Press 'F8,' and on the next screen pick the hard drive you want to format and install Windows XP on. Then, click 'Next.'
4. Wait while setup installs Windows XP. Most of the process is automatic, but at times it will stop the installation and wait for you to enter in information or choose options for the operating system. You have now installed Windows XP despite the Bootmgr file being missing.