There's a difference. I choose not to upgrade because of convenience. You can't upgraded because IE has not received an update in over three years, despite horrendous security holes, and atrocious CSS support.
IE is great only in that it comes with windows, giving me a method to download Firefox.
I have never had a virus, and only once had a spyware problem, which one of my spyware programs fixed, this year, when I finally got the software for it.