Personally I like the portable edition because you can always copy it onto a USB drive or use it on an other computer without having to reinstall and set all your settings.
What's new from Firefox 2 Beta2 to Firefox 2 RC1?
- ->The interface theme was refreshed and looks a lot better now
- ->all other changes are tweaks to what was already in Firefox 2 Beta 2 or bug fixes






for a complete few click on the image below

What's new in Firefox 2 in general?
- ->Spell Checker: Whatever you type (e-mails, blog posts, forums...), Firefox 2 will underline incorrectly spelled words. On right click it will give you suggestions for alternative spellings just like Word.
- ->Subscribing to RSS feeds has become a lot easier. You can now add an RSS feed directly into your Google Reader, Bloglines ...
- ->Improved Add-on manager
- ->Anti-phishing protection. Firefox will alter the user about websites that pretend to be something like a bank but in fact only want to get access to you account name and password.