At the time of writing this guide, OS X 10.5 Leopard was the current release by Apple. The newest OS by Apple is OS X 10.7 Lion. The installation procedure should be relatively the same as previous versions, although, you will need to first create a Lion Recovery Disk using [http://support.apple.com/kb/dl1433|this tool] provided by Apple.
Install Mac OS X v10.5 Leopard on a new hard drive.