I've been involved for a couple of years in developing Linux-Apache-MySQL-PHP/Perl/Python apps for various clients. During most of that time, I've used in-house Linux servers for prototype, development and testing, and Linux servers deployed at the client site or a hosting provider for production work. Recently, I wanted to spin off a second copy of an application on a local Windows laptop to test some radical changes while the rest of the development team continued to work away on the dev server. Ideally, I wanted to install the entire LAMP set on my local workstation without a lot of work, configuration, downloads, HowTos, and so forth. XAMPP offers free, prepackaged installation modules for Linux, Windows, OS X and Solaris, bundled with a dozen handy utilities like PEAR and phpMyAdmin. Installation was a click, click, click, done! process. Reading a few READMEs got a few non-standard settings like enabling InnoDB data storage. Slick!
If you need a quickly set up XAMPP stack, you'll want to check this out.