The default location for the boot.ini file is the C: directory, or the root directory. It may be hidden by one's system settings by default, to prevent any alteration or deletion of this important file.
To edit it, the C: directory must be configured to display hidden files. The extension ".ini" is for initialization files, containing information used when the operating system, or other pieces of hardware, are first started up. The boot.ini file tells Windows what to do when it is first started up, how long to wait for the user to select what operating system is used, and what hard drive the operating system is on.
Fixing a missing boot.ini file can be done through the XP Recovery Console, by typing the "bootcfg /rebuild" command and hitting enter. Then, typing "yes" once the scan is completed, and then listing what operating system to use. Finally, type in "/fastdetect", and then hit Enter. This process will require the Windows disc to be inserted.