I just downloaded the latest version on a whim, and wow do I love it!! It looks a bit similar to Netscape, but there's a lot more than meets the eye. The browser runs siginificantly faster than IE, less buggy, less holes (since it's open-source so normal users can help improve it). Tabbed browsing I now couldn't do without, it's just great (it lets you browse multiple sites in "tabs" at the top of the browser instead of cluttering your windows toolbar). It also has built-in pop-up stopping and a download manager that's actually functional and not annoying! The full version even includes a top-notch email and IRC client. Great stuff, and it's 100% free. Give it a shot!! I know... many people are very very attached to their Internet Explorer or Netscape... but give it a whirl, you'll fall in love!!
Oh! One last thing! It's carried over all my plugins (except for Flash for some reason). No need to reinstall!!

www.mozilla.org