After using FireFox for ~3 weeks, I have to say I like it. It has given me no trouble whatsoever, kills every popup every time, and has yet to give me one glitch. It seems to be extremely navigation friendly, gives lots of options on how to set up bookmarks and favorites, and the Bookmarks Toolbar is a nice convenience.
It's free, and you can downlaod it from www.mozilla.com.
I think the free, open domain status is one of its protections against viruses, etc.