My brother, who doesn't like the bells and whistles (I think he calls it the bubbly look) offered by Windows, prefers the basic style of Firefox. Plus, he claims it's more secure. He works extensively on and with computers (Linux is his platform) and swears by Firefox, as well as Pegasus for email.
I have both Microsoft IE and Mozilla Firefox on my computer, and only have to choose which web browser to open my sites with. The Firefox download is free, and it has yet to hurt any of the computers I've owned. There is something to say about the sleekness of it... AND now I'm sold even more, because of the spell check feature. It underlines misspelled words as you type them just like MS Word does when you're composing a Word document.
I tried Mozilla Thunderbird, but didn't really care for that... I'm still an MS Outlook fan... guess because I teethed on it.