Microsoft Knowledge Base Article 289022 contains the following summary:
This article describes how to view and manually configure the Boot.ini file in Windows XP from within the Startup and Recovery dialog.
In Windows XP, you can quickly and easily locate the Boot.ini to verify and/or edit the file.
It is suggested to backup the Boot.ini file before editing. The first tasks will involve modifying folder option so as to view hidden files and then backing up the Boot.ini file.