another tiny one from ASUS
Asus Eee Box It doesn't come with Windows XP but it's cheaper than FIT-PC2 and it has 2GB. I am sure you can install Win XP on it and use it as a remote server with remote desktop software.
However it's twice bigger than FIT-PC. I've seen it for sale on a computer swap. It's still small and slim but it's longer and wider than FIT-PC2