I remember reading somewhere that there is a way to set up a configuration file which Debian-Installer can read (so, essentially, you pre-select all of your answers). I have never done this myself, so I cannot tell you anything else. I think I read it on debian.org, if that helps. I am not sure that Sarge has support for it. I am 99% sure that Etch does. I actually suggest that you install Etch (or wait a month for it to become stable).