I recently built a really small and quiet home server that ran Windows Server 2003 based on a mini-ITX motherboard. It turns out you can build a great system in a very small package. The only down-side is that the really nice cases are pretty expensive compared to larger cases driving the total cost up.
The system I bought was a Casetronic C134 based system from LOGIC SUPPLY. With no OS, a 20gb hard drive and 512MB of memory (256MB would have worked fine, but I always like to go overboard on memory). The total cost was $503.50 without shipping.
This device will make a great infrastructure and/or automation server. The fact that it can only house a 2.5″ laptop hard drive means it’s not ideal as a storage server, although you can use external USB drives. If you want it to be a router, using either Windows’ built-in router/firewall support or ISA 2004 you could add a USB ethernet adapter.
Performance wise, it’s amazing how well Windows Server 2003 runs on a machine like this. Setup is quite slow, but once the OS is installed it is certainly fast enough for to support a small network. I tested it as a file server, an active directory server, DNS and DHCP server, and even with sharepoint.
The Casetronic C138 mini-ITX chassis has room for a 3.5″ hard drive as well as a single PCI slot. It would be killer if there was a case like this that had room for 2 3.5″ hard drives so you could enable RAID 1 mirroring via software in Windows. But, alas, I have not found one that was as “tight” as these Casetronic units. For example the Morex Venus 668 appears to fit the bill but is actually just as big as a Shuttle “cube” style computer. The mini-ITX mobo is tiny inside and there’s tons of wasted space.