This is a file needed to start windows NT systems, you have your windows XP disk, so your in luck:
1. Insert the Windows XP bootable CD into the computer.
2. When prompted to press any key to boot from the CD, press any key.
3. Once in the Windows XP setup menu press the "R" key to repair Windows.
4. Log into your Windows installation by pressing the "1" key and pressing enter.
5. You will then be prompted for your administrator password, enter that password.
6. Copy the below two files to the root directory of the primary hard disk. In the below example we are copying these files from the CD-ROM drive letter "E". This letter may be different on your computer.
copy D:\i386\ntldr c:\
copy D:\i386\ntdetect.com c:\
(Where D: is enter your CD-ROM drive letter, Normally D:, To find out what drive letter to use, Go through them one at a time, then enter:
DIR
and look for the i386 folder, this is the drive to use to copy the files from)
7. Once both of these files have been successfully copied, remove the CD from the computer and reboot.