(This is 2000 Pro that this happened so i hope irs not of the topic.)
I had this happen to a laptop yesterday at one of my schools, what i did was copied NTOSKRNL.exe from another system and then booted the corrupt system up with the XP CD, once in the recovery console i removed the XP disk and placed the disk with the new file in the rom, (could not use a floppy because the file 1.66MB) i copied that file to \\[system]\system32 then restarted. Booted up fine.
3 hours later it crashed and a new hard drive is on its way, however, igot the data i needed to backup of it.
I hope this helps in some way.
Jonno