The site is running a typical LAMP environment.  The software versions noted below were installed on the servers at the time this was written.  So, I guess one could call this the "baseline."  

• Operating System – Debian Linux with 2.4.29 kernel
• Web Server – Apache 2.0.54
• Database Server – Mysql 4.1.16
• Script Processor – PHP 5.2.3
• Application – Drupal 6.x CMS