I once downloaded Opera but never installed it since I was satisfied with Netscape. I did upgrade Netscape to version 6.2.x but found that horribly slow on my old equipment so I went back to Netscape 4.7x which I find perfectly adequate for my simple needs. (I actually also keep installed a version of Netscape 3.x since I prefer its newsreader.) As FL310 mentioned you don't have to install the complete "browser suite", Netscape Communicator, if it is not needed. Just download and install the browser, Netscape Navigator. The installation instructions at
http://www.netscape.com/comprod/mirror/ are comprehensive. All past releases and other stuff are available from the page
http://home.netscape.com/download/index.html