Getting Mozilla
Sadly, the Mozilla program is a major download and you need a lot of your own software to do anything with the source code (a compiler for a start). Worse, with all the program libraries you need and all the modifications you need to make to adapt the code for your local situation, compiling the code isn't a simple task. It requires a fair bit of programming experience, a lot of patience, an amazing amount of time, and a heroic amount of determination. Fear not; there are places where you can download fully compiled ready-to-run executables (although only for Windows 95 or Windows NT). Four places I can recommend are http://www.wynholds.com/mike/mozilla/, http://www. mozilla.org, http://www.mozillaZine.org, and http://mozilla.hypermart.net/. (The generosity and open-heartedness of quite a few people on the Internet continues to amaze me, even after 12 years of being online.)
Installing the program is very easy and, with a small modification to your Netscape Communicator profiles, it happily coexists with any other browser (unlike IE5, which replaces a lot of files that are essential for running IE4).