There are pros and cons to building Mozilla yourself. The biggest drawback is that the source version, compressed, is a 30+ MB file in most releases which is about three times larger than the binary distribution. A second negative is that on a reasonably new machine such as my 1.6 ghz Pentium 4 with 256 MB of memory, compiling Mozilla can take anywhere between one and a half to four hours depending on any other jobs the system might be running. On an older machine, Mozilla can take twenty-four hours or more to compile. The biggest benefit is that there are a large number of compile-time options and patches that can be applied which will dramatically improve the performance and featureset of the browser. These patches are generally necessary if you intend to run Mozilla in a production environment.
If you are not interested in source level modifications of the Mozilla browser, please skip the next few sections and have a look at Section 7, Post-Install Configuartion.
At the time this document was written, the latest version of the Mozilla source code is 1.2.1, which can be obtained via ftp at ftp.mozilla.org/pub/mozilla/releases/mozilla1.2.1. The other stable release, 1.0.1, can be obtained via ftp at ftp.mozilla.org/pub/mozilla/releases/mozilla1.0.1.
For CVS checkout, please review the documentation on the Mozilla website.