Firefox is ok for basic websurfing, but it doesn't do Java very well. Also many of the plug-ins don't work with it. Its tabbed features and extensions are leaps ahead of IE.
I do enjoy some of the extensions, such as the ability to remember passwords even on sites that try to prohibit that. Is there a system you recommend as an alternative to IE and Firefox?
Batten down those "cookie hatches" Ad-Aware and Spybot will NOT detect tracking cookies from Firefox. It uses the old Netscape cookie format that puts them into a single text file and those programs will not see them. I use accept only from originating site and delete when closing Firefox with good results but you can make it tighter.
Sage Project Wiki, check out the tutorial under getting started.