You just download Firefox and use it.
When you want to browse open FF instead of IE (put an alias on your desktop). You may have to do some tweaking of your system preferences to make FF the default browser or FF may do it for you. I donno, I've never used Windoze except to get it set up on Mac networks. Windoze guru's can help you with problems. Besides, I always think it fun to try new software.
I use 4 different Browsers for different things (and a have about 20 all together I can use). I often have all 4 running at the same time.
I am not sure if it is possible to delete IE from Windoze. Ain't that what the lawsuit was all about?