Yes, it is free.
I would recommend Mozilla Firebird over the standard Mozilla for the new user, it's much easier to get used to, and is just a browser. The mozilla suite (what I use) has an IRC client, email client, address book, and HTML editor built in.
You can read about it at
http://mozilla.org/products/firebird/why/
There's a download link at the bottom.
Give it a week of exclusive use and you'll never go back. Remember, middle click (or ctrl-click if you are mouse-wheel-less) opens a new tab.