http://meta.wikimedia.org/wiki/Installation
Prerequisite tools
To install MediaWiki you need four components:
* MySQL - an SQL database to store the Wiki text, user list etc.
* Apache - a web server to serve the HTML web pages
* PHP - the programming language that MediaWiki is written in
* MediaWiki itself, which is a suite of programs written in PHP
Minimum system requirements
Slow performance has been reported on systems where the whole site is on a single Pentium 133 with 48MB of RAM. 256MB is the recommended minimum amount of RAM for a single computer site but you're certain to need more for a busy public site. The Wikimedia Apaches typically have 512MB to 1GB and the databases servers 4GB.