Computer Stuck At Update Screen

My computer is stuck at the windows update screen when I boot it up. A week or so ago I had some trouble installing a program. Looking for a solution, eventually I found that my windows hadn't been updating for several months. Trying to update manually didn't work and I got an error message. Googling that error message was what brought me to vistax64.com in the first place, and after reading around a bit I managed to determine that I was missing my Windows Update Module (unsure about the exact name). I followed a tutorial that led me into regedit to delete some keys. Now, to the matter at hand: after deleting these keys and restarting, my windows got stuck at the update screen. It says something like: "Configuring update 3 of 3 - 0% Do not turn off or bla bla bla" for a few minutes, without the percentage changing, then restarts. Problem is, when it restarts it displays the exact same message and does the same thing all over again. So it gets caught in a restart loop. I have tried booting from my Vista DVD and have tried the startup repair thing, but that isn't any help. I don't have any save points to restore from, nor a backup. So - the question is: Is there anything I can do about this without having to format and reinstall Windows?