Apache2Triad comes in three different configurations; a legacy version for Windows 9x systems, and PHP4 and PHP5 versions for Windows XP. If you intend to work on a copy of Drupal that you plan to transfer to a production server provided by your web hosting service, you may wish to find out which versions of PHP and MySQL are installed. If your web hosting service is currently providing PHP/MySQL 4.x, you may wish to download the corresponding version of Apache2Triad, in order to avoid compatibility issues. If so, you may also wish to inquire your hosts' timetable for upgrading PHP and MySQL since 4.x versions are no longer supported by their respective development teams.
As of this writing, the following versions of Apache2Triad were available for download from Sourceforge:
Edge (Apache2.2 PHP5 MySQL5) v1.5.4 95.8MB space required 348.7MB
Stable (Apache2.0 PHP4 MySQL4) v1.4.4 75.3MB (somewhere between "edge" and "legacy")
Legacy for Win9X (limited Apache2.0 PHP4 MySQL4) v1.2.3 48.0MB space required 200.3MB
While each version of Apache2Triad shown has been tested with various versions of Drupal in recent years, this tutorial focuses on using the "edge" version as installed under Windows XP. (Note that Drupal 7 will require PHP5.)