A while ago I bought three fit-pc's (yes, three) with the intention of using them as servers for various purposes in our house. I quickly set up one as firewall/gateway, as I prefer a simple linux/iptables based firewall setup instead of a closed SOHO router (from any vendor). Anyway - the fit-pc comes with Ubuntu Gutsy (7.10) Desktop preinstalled, so I quickly decided to wipe in and reinstall with Ubuntu Server. Unfortunately I never managed to get it to boot from usb - cd or flash. After running around on the fit-pc wiki, I decided to give netboot a shot. It turned out to be very easy. My first installation was done using this howto, but as I afterwards shut down the server running tftpd-hpa and I needed to install another fit-pc I had to get a tftp server running again.
The above howto mentions that is doesn't work using Unbuntu Hardy, but luckily someone also created another howto which (as the name implies) is even simpler than the first one. The installation is currently at 66% Configuring the base system.
Oh, and by the way: the server is to be used in our office, as printer and scanner server, using cups and saned, serving both linux and (hopefully) windows clients. More on that later.