It really depends on what you are going to do with the machine. Dual-screen probably means you're developing and/or running office apps on it. In that case, the cheaper Intel Atom desktops won't be able to cut it. They can be had for 300 EUR and are suitable for internet surfing and basic office use, but not for games and CPU-heavy apps. The Via Nano and Nvidia Ion series are a _little_ higher end, but any Core2Duo will beat those anyway. I'd check out a few barebones, but the only manufacturer coming to mind is Shuttle - which you want to avoid. Hmm. You could check out the Mini-ITX-boards the web has to offer, as well as the corresponding cases.
Cheers, Sebastian -- "If it was two men, the non-driver would have challenged the driver to simply crash through the gates. The macho image thing, you know." - Marc Clifton