The first thing I want to do is get rid of the monitor and keyboard, so
$ sudo apt-get install openssh-server
$ sudo apt-get install screen
(Screen is great. I use it whenever I need to kick off some long-duration command. It means I can close the laptop, dropping my ssh session, but still reconnect to the console running the command whenever I want to.)
Edit /etc/network/interfaces to change from DHCP to static IP address, which is covered well here.
I never tried this before...
I ordered the serial cable with my fit-PC and got a €3 generic USB RS-232 adapter cable from this store on ebay.
The instructions on the fit-PC wiki were great. On the other side, all I had to do was check which COM port the USB adapter was on using Windows device manager, and then create a serial PuTTY session using the same configuration.
With this setup, I get GRUB and kernel output to, and login from, the serial console. This is a real bonus compared to my old PC server.
I'd really like to be able to configure the fit-PC BIOS over the serial connection as well, but it sounds like that might be a bit more difficult.
Anyway, BIOS configuration changes aside, I can ditch the keyboard and monitor now. My fit-PC is ready to be a headless server.