Suddenly the browser wars are just flat blowing up. Google released its latest version of Chrome last week. This week saw the release of Internet Explorer 9 from Microsoft. And next week will be the debut of the latest version of Firefox. Like IE9, it will work with the fancy new HTML5 sites that are on the way. Unlike IE9, it will also work with Windows XP versions. Think about that: 50% of PCs are on XP but Microsoft won't support them with a new browser. Weird. I guess they want everyone to upgrade but still: weird.
Microsoft reports 2.3 million downloads of IE9 in 24 hours so things are going okay there, I suppose.
I suspect that the associations people have with a browser have less to do with specific capabilities than they do with habit and brand identification. If you've always used IE, you'll probably keep using it. If you decided to be daring and avant garde a few years ago, you're on Firefox. If you spend a lot of time on Google, you may have taken it up on its repeated offers to switch to Chrome.
What's the ultimate experience difference on each? I couldn't tell you. But the big companies are pushing hard right now.