I'd be interested to know if there are any other mainstream websites that use ActiveX nowadays, apart from windows update? I use a mac and haven't really come across any sites that require it, apart from windows update. Annoyingly I wanted to access windows update for a friend on dial-up recently (computer continuously rebooting, uses an anti-virus program but never updates and no firewall), and couldn't download anything as it's broken in other browsers, there was no alternative given. The updates are really too large for her to download at home. I really don't see why they would exclude other browsers apart from to try to lock down their users to use their software and platform.

Frankly, when I find a message in a browser window that tells me the browser is checking my version of windows (as happens on Windows Update), that really worries me.

If that's the only mainstream one that requires it, why not use another browser most of the time and just use Explorer for Windows Update? There are so many other advantages to other browsers (standards support, pop-up blocking, tabs etc) apart from security, that the question should really be :

'Should you keep using Internet Explorer^TM?'