Obtain a LiveCD distribution, such as Morphix, from http://www.morphix.org. See Section 4.3.3 for details and Section 3.1 for other distributions of Debian GNU/Linux. Boot your computer from this CD and you will have a running system (but not yet installed). Then ask Morphix to install itself. You will end up with an installed Debian GNU/Linux system, but it will have some subtle differences to a standard Debian install.