security update wont install(error code 643)

Im trying to install the following: "security update for microsoft .Net framework,version 1.1 service pack 1 (KB929729)"

I get the "failed install" prompt everytime. Everything I try doesnt work. I went to the microsoft knowledge base and forums and tried the following:
"Download and run the Windows Installer Cleanup Utility, and remove the ..NET framework 1.1 from the machine.

Download .NET framework 1.1 from the Microsoft website and install it

Reboot your machine, then install .NET 1.1 SP1 from the Microsoft website and reboot your computer again. Then try to take the update once again."

Nada. any help apreciated..