Well, since IE hasn't care about webstandards and most/alot of websites were not designed to work in muliple browsers, I guess the internet would be pretty boring, because not many pages would render properly.
Take a look at http://mondays.pwop.com In Firefox.
This is only a minor glitch. I've seen pages all backward and upside down. I've seen pages that don't even show anything in browsers other than IE.
This forum doesn't render properly in Firefox. But it's not too bad. I like the extra buttons you get on the video windows in IE.
I thought Konqueror was great at first, but then noticed that it was pretty bad.
I hate using Opera, but if that was all that was around, I'd guess I'd use that. I don't know what Opera is based on, cause I don't care about that lame browser.