I just installed Debian (again) and had to look around again to find out how to stop using 100dpi fonts, which are too big for my liking. I finally found a thread on Google Groups that mentioned the files to change.

This default can be modified by editing the following conffiles:

    xdm     /etc/X11/xdm/Xservers           (see xdm(1))
    xfs     /etc/X11/fs/config              (see xfs(1))
    xinit   /etc/X11/xinit/xserverrc        (see xinit(1))</blockquote>

Ah, much better.