Install the drive as a slave drive on a working computer. Backup all your personal files to DVD, etc...Reinstall the bad drive, reformat, and do a fresh install of the operating system.
Something has gone terribly wrong with the Registry. It could indicate the Registry received an I/O error while attempting to read one of its files as a result of a hardware problem or file system corruption.
You better slave your drive and pull off your information, your going to have to format the drive and reinstall Windows
Read more: 0x00000051 error while installing Windows XP (RESOLVED) - Tech Support Forum http://www.techsupportforum.com/forums/f10/0x00000051-error-while-installing-windows-xp-resolved-154201.html#ixzz1FQ7ZmyOJ