Check this article to find out info on how to install and use the recovery console for Windows XP:
http://support.microsoft.com/kb/307654If you already have the recovery console, or got it installed using the above tutorial, then do the following:
Using the Recovery Console, copy the Ntldr file from the Windows XP CD-ROM to the root directory of the current active partition. Follow these steps:
1. Start your computer by using the Windows XP Setup floppy disks or by using the Windows XP CD-ROM.
2. At the "Welcome to Setup" screen, press F10, or press R to repair.
3. Press C to start the Recovery Console.
4. Copy the Ntldr file from the Windows XP CD-ROM to the root of your system partition by using the following commands, pressing ENTER after each command:
1. Type cd .. to go to the root of drive C. (Note the space)
2. Type the letter of the CD-ROM drive
3. Type cd i386 to change into the right directory
4. Type Copy ntldr c:
5. Type Exit
If this does not work, then do the following: To replace the boot sector, at the Recovery Console command prompt, type: fixboot [drive:]
If you do not specify a drive letter, the Recovery Console replaces the boot sector of the system volume. If you need to replace the boot sector of a volume that is not the system volume, then you must specify the appropriate drive letter."See if this works.