Go Control Panel->Programs->Programs and Features->View Installed Updates (that last one is from the left-hand column) and then select the update and choose the Uninstall option. You can then block it from being downloaded again, at least in the near future.
Hope this helps,
How do I uninstall HOT fix KB891781? It is screwing up my html editor (Homesite 4.5.2) and I want it GONE! I do understand the risks of removing this and on balance I am willing to risk it. I know how to remove it in Windows XP but I couldn't find the uninstall program.
I looked in the Control Panel and then did a search on my hard drive.
I also want to stop it from ever downloading again. I can do this on the windows update site by using Custom updates, but I have to remove it first.