The Windows PostGIS Installer is superfluous because the native Windows PostgreSQL installer now already contains PostGIS. Please use the PostGIS version provided in the PostgreSQL installer.
To ease the PostGIS installation on Windows, a PostGIS installer has been created for DCMMS. The DCMMS documentation contains more information on the installer.
Before you start the installer, you have to install the PostgreSQL using the PostgreSQL installer available from http://pgfoundry.org/projects/pginstaller. The DCMMS Administration Guide and the PostGIS Windows Installation Tips contain additional information.
For those interested, the installer sources (including a script for the complete removal) are available.
PostGIS is created by Refractions Research Inc, the PostGIS homepage is postgis.refractions.net.
PostGIS is released under the terms of the GNU General Public License (GPL).