Why not spend just a little money, and include a USB disk-on-a-stick? On boot check to see if a "control" file is there (or has the right datestamp, md5sum, whatever), if it isn't, format the drive, extract the tarball to it, prompt for config info (point at their ldap/exchange/etc), save it the config, start services, start demo. If control file exists and is "proper" the just start services and demo.