These are instructions for setting up a server environment for Pentaho. It is based on what we do internally at BizCubed. For setting up a development environment, see here.
Hardware: As an enterprise-level application, Pentaho can be quite resource-hungry. You should have a fast CPU and 1GB of RAM (you can make do with less, but it'd be frustratingly slow).
Operating system:CentOS 5.1 x86_64 (this is identical to Red Hat Enterprise Linux 5.1)
Java
See the Install and Configure Java page to get you started, and the Java page page for further detail on setting up and optimising Java for Pentaho.
Grab the latest Pentaho GA release from SourceForge. If you only want a trial, you can use the Hypersonic (HSQL) version. For production use, the MySQL version is recommended.
Extract the downloaded archive to where you want Pentaho to be installed.