There are several sites which can only be viewed correctly with the Internet Explorer, e. g. the Windows update site. IE Tab has a list with such sites, and if you go to a “site for IE”, it switches to the IE engine.

You can download IE Tab for free at mozdev.org:
http://ietab.mozdev.org/
What do you think? Do you often visit these sites?
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Wonderful!
It’s a good idea, much like Netscape did.
Can you tell me sites sites that need IE? The only I know is WindowsUpdate, and I never had problems with Firefox.
Alex