Specifically...what "fix" did you run and did you follow the directions reflected in such?
If you are referring to one of the removal guides, and particularly, the one for XP Anti-Virus 2011, please note that the following is part of that guide:"If you have any questions about this self-help guide then please post those questions in our AntiVirus, Firewall and Privacy Products and Protection Methods forum and someone will help you."
<<I honestly think the REAL problem is that when I ran the fix from this website for the XP Anti-Virus 2011, that it deleted a necessary registry file and I now need it.>>
From what I see...the Win Update error you mention is very common and I really don't see a definitive solution that I would suggest.
If you think key system files are missing/damaged...it's probably best to either try a repair install of XP or try running the sfc /scannow command with a CD reflecting the same SP as your system currently has.
How to Perform a Windows XP Repair Install (Stevens) - http://www.michaelstevenstech.com/XPrepairinstall.htm
How To Use Sfc.exe To Repair System Files - http://www.bleepingcomputer.com/forums/topic43051.html