Debian Installer preseeding: autostart from PXE

Assume that you have a fully working Debian Installer preseed configuration. Your x86 target machines do not have CD-ROM drives (and handling CDs is cumbersome), booting from elsewhere is not really an option.

Solution: boot from PXE.
DHCP, tftpd-hpa and pxelinux are set up easily in just a couple of minutes.

Here's the pxelinux.cfg configuration as needed to make the installer enter silent mode:
label auto
kernel debian/etch/amd64/linux append vga=normal initrd=debian/etch/amd64/initrd.gz DEBCONF_DEBUG=5 -- auto url= locale=en_US interface=auto console-keymaps-at/keymap=us debian-installer/country=AT hostname=installme
This will set up an English/US locale, US keyboard, set the preseed.cfg path and kick off installation. Hostname and domain are optional, but can be used to override the values from DHCP. DEBCONF_DEBUG=5 is quite useful to see what's currently happening. While the installer is running you can switch to console 4 to see what's going on. After the installation has finished you can take a look at /var/log/installer and see what happened. Saves quite some time while debugging late_scripts.