IE and Netscape both have issues... IE just renders pages faster. I like Netscape's UI better and the fact that it does my email too. It also doesn't install hoards of extensions that slow the machine and could possibly cause conflicts.

As for OS X.. I'm going to do it as soon as I have the money, I'm still gonna keep a partition for OS 9. I plan to put OS X on it's own seperate hard drive though.