I started using Firefox when it was first released and have not looked back at Internet Explorer (IE) since. Firefox is faster, better, customizable, and more secure.
I used to help one of my friends with his computer problem every few months. It used to get all sorts for viruses and what not. So I'd backup the data and re-install Windows every few months... that is until I finally installed Firefox on the computer after rebuilding it for the last time. I made it the default browser and have not been called back to *fix* the computer after that :)
To Each His Own. I'd recommend giving it a try; you might like it.
I still use IE when I'm at my bank's website and other sites that seem to work only on IE; Firefox has a extension for that too!
Installation: You can get Firefox from http://www.mozilla.com/en-US/firefox/
Getting Started: Nice tips http://www.mozilla.com/en-US/firefox/tips/
Extensions/Add-ons: There are LOT's of add-ons available for Firefox that let you customize the browser to your liking.
You can search from the browser itself by going to: Tools > Add-ons > And click on the "Get Add-ons" tab or going to https://addons.mozilla.org/en-US/firefox
Here is a list of all the extensions that I have installed on my Firefox:
And that not the complete list. I probably have all these and a couple more installed on my personal machine at home. If you want a feature then it's very likely that someone has already created an add-on for it. If you are interested it is easy to create your own add-ons and write Greasemonkey scripts.
Have fun browsing on Firefox :)