As I stated in the response to another post on this subject I would advise you to contact Technical Support by phone or online chat. It's free and linked under Useful Links at the top of this page.
This sort of thing is a bit too technical for us to troubleshoot in the forums. Googling KB286330 shows that there have been problem reports with other software too, so maybe a subject for Microsoft Forums too.
It would appear to me at least that it's Microsoft who needs to correct the issue. Meanwhile other companies such as McAfee could indeed do a workaround. Technical Support is best for that.
I amended the post above but should add, if an antivirus fails to install, the prime suspect would be either infection or traces of a previous similar product of either the same brand or a rival one. You might want to check those aspects too.
That's great news for us. Kindly provide the below information so that I can reproduce the issue and isolate if the issue with the Microsoft update.
Operating System: Win XP SP3
Version of IE :
Version of McAfee Installer: