First things first: DON’T TELL ME TO SWITCH TO LINUX!!! :<
Okay…Windows XP comes up with a BSOD(Blue screen of death) that says:
STOP: c0000221 Unknown Hard Error
\SystemRoot\System32
tdll.dll
I read this, and I identified it as the same problem, but How can I replace the file, if WINDOWS DOESN’T COME UP?! :<
Anyway, thanks in advance.
boot into safe mode (1. Restart your computer and start pressing the F8 key on your keyboard. On a computer that is configured for booting to multiple operating systems, you can press the F8 key when you the Boot Menu appears. 2. Select an option when the Windows Advanced Options menu appears, and then press ENTER. 3. When the Boot menu appears again, and the words “Safe Mode” appear in blue at the bottom, select the installation that you want to start, and then press ENTER.)
in safe mode it should boot up correctly where you can fix the problem and than reboot into normal windows
…or you could just switch to linux 
;)
I don’t know if this would work for you, so don’t try it until you know for sure that it wouldn’t screw up your machine…
Go on another computer and download the file you need, and put it on a floppy disk.
Then, get like a windows 98 boot disk or setup CD or something, and make sure the computer boots from cd (or floppy, depends on what you’re using)… put the boot disk in and turn the computer on (the broken one, that is). Then when the Windows 98 text-menu thing comes up (you should see what i mean), select not to start windows setup, and instead boot the computer with cd-rom support (or not… you’re preference, since it doesnt actually boot XP) or to just go to the command line.
Then, it should put you into a dos prompt. Then put in the disk with the file you downloaded, and copy it to wherever i’m assuming that page told you to (i didn’t read it…). If you don’t know the copying command for dos, i’m sure i can find it… Anyways after it’s copied, just take out all disks and reboot the machine (making sure it now boots from the hard drive instead of cd/floppy).
Alternatively you can put the broken computer’s hard drive into another computer set as a slave, and then copy the file directly onto it, and then put it back in the now-probably-fixed computer and boot it.
Like I said, don’t try any of these until you consider more things and/or other people agree with these. also, PLEASE dont hold me responsible if your computer doesn’t work after, lol… hey it’s fair, i warned you…
EDIT- the safe mode thing would prolly work better, but here’s these just in case it won’t let you do that.
Ok, I repaired with the boot CD, so I guess I’ll have to re-install SP1 and all those updates. 
You have my simpathy(?), I had a similar problem(but turned out to be a bad HD connection :x ); I had to re-install XP and all the drivers, programs, etc…it also erased my blend files(but not python thankfully!)…
get linux 
im just kidding of course. I’m not fermiliar enough with linux to stand by it.