For installing on multiple computers it's possible to do fully automatic installations. Debian packages intended for this include fai-quickstart, which can use an install server (have a look at the FAI home page for detailed information) and the Debian Installer itself. The FAI project also provides a web service for creating customized unattended installation ISO images with only a few clicks. You can choose the desktop environment, the language, the release, set the password and add your own list of additional packages. After a few minutes your can download and boot the image, that will do the fully automatic installation without any interaction needed. Some more advanced settings are available for Linux experts.