if you have a OEM disk you will have to borrow a XP OEM or retail disk to do this...
Users who have a corrupt or missing boot.ini file, are running Microsoft Windows XP, and have a Microsoft Windows XP CD can rebuild the systems boot.ini file by following the below steps.
1. Insert the Microsoft Windows XP CD into the computer. Note: If you have a system recovery CD or restore CD these steps will likely not work for your computer.
2. Reboot the computer with the CD and press any key when prompted to press any key to boot from the CD. If you do not receive this prompt and/or are not able to boot from the CD see document CH000217.
3. Once in the Microsoft Setup menu press R to open the recovery console.
4. Select the operating system you wish to use; if you only have Windows XP on the computer you will only have one prompt.
5. Once prompted for the password enter the Admin password and press enter.
6. Once at the command prompt type bootcfg /rebuild to start the rebuild process.
7. The rebuild process will step you through a number of steps depending upon how many operating systems you have on the computer and how the computer is setup. Below is a listing of the common steps you are likely going to encounter.
* Prompt for the identified versions of Windows installed. When you receive this prompt press Y if the bootcfg command properly identified each of the Windows operating systems installed on the computer. It is important to realize this command will only detect Windows XP, Windows 2000, and Windows NT installations.
* Prompt to enter the load identifier. This is the name of the operating system for the boot.ini. For example, Microsoft Windows XP Home users would enter "Microsoft Windows XP Home edition".
* Prompt to Enter OS load options. When this prompt is received type /fastdetect to automatically detect the available options.
8. Once you have completed all the available options in the rebuild and are back at the prompt type exit to reboot the computer.