Yes. I have Internet Exploror, Netscape, and Opera all loaded on my PC.
I use Internet Explore most of the time, while my wife uses Netscape. (This is mostly because of sites which use cookies for sign ons and such.) (For example, this site - in IE, It has my signon all ready. In Netscape, it has her signon all ready!)
(I mostly use Opera for testing my own webpages to make sure they look good.)
Cool thing about the newer Netscape is that you can use tabs instead of windows for different pages!