OK, there is nothing wrong with SP1.
It looks like it got corrupted during the download or
your system got turned off during the install.
Can you go to safe mode? If so, and you archived your files, you can do an uninstall.
If not, then re-install from scratch, clean, but DO NOT FORMAT or DELETE any partitions.
During the install, it will ask for what partiton to install on, pick the one you have. Then when it ask to do a New install, do it and put it in the same folder.
This will wipe Windows, but not your drive. You will need to re-install all the programs but the data will still be there.
I recommend you use a different user name so your old one is not touched. Then after starting up again, copy your Doc, OE, tec to your new account. The folders will still be there.
I made the mistake of downloading SP1 for XP and now it just keeps trying to boot but gets to the XP screen for about 3 seconds and reboots itself. I can see safe mode and try to boot that way but the same thing happens, also i tried to have it boot to the last known good configuration but it just keeps rebooting. I tried to use a recovery disk but it did not work either. I could load XP again but I can't afford to lose the stuff I have. Any help is appreciated.