It's really a question of what you are used to and what you like.
I am increasingly of the opinion that Firefox may offer some added security, but as it becomes more popular it's been targeted by hackers/spyware etc..
Firefox has tabbed windows, so you can view multiple sites easily. It doesn't rely on underlying (vulnerable) Microsoft technologies like Active X controls, but that makes it impossible to use on some sites
Opera claims to be the fastest browser on the planet - has tabbed windows and inbuilt email client.
Netscape offers many good features.
Internet explorer is only as big as it is, because of Microsoft's dominance of the operating system market and because they've integrated it into the operating system.
They didn't need to do this, but they want total dominance - so I avoid Internet Explorer out of general principle, unless I need to use it.
DaveB - LinuxWannabee