You can get the file from the latest ntoskrnl update. Download Security Update for Windows XP (KB2859537)
I presume you are not able to boot the computer and you are at a different computer. If so, download it to your desktop, click start, run, browse, browse to the file and double click it. The path will now be in the run box. Add a space and /x after .exe and press enter. A dialog with your desktop path will be shown. Add a \ and a folder name after Desktop. I suggest KB2859537 for the folder name. Press OK and the files will be extracted to that folder. In the SP3QFE folder, you will find the file.