I once was a faithful NS user. I removed all links to IE from my computer. I refused to use IE (AND MSWord, MSthis, MSthat...) I hate Micro$oft!!!
Not now, though. NS crashes too often, and takes a while to load. It also has less features than IE. But I changed for only because a friend told me to stop using NS, with good reasons. He said that the NS4.7's sucked, and told me that if I really want to use NS, then go with Navigator 4.07 or 4.08, which is simpler, loads faster, and doesn't crash as often.
I'm using IE5.5 as my default browser now, and made NS my secondary, and use Opera to download files (I liked their Download window) and quick browsing. I don't dare try NS6, heard too many rumors about it.. but if NS ever publishes a new browser, I'm willing to try it, and switch back if NS has made improvements.