Hardware
You could put together this server with any PC hardware, but my main priority was to build a quiet (ideally silent), small system at a reasonable price.
I discounted the idea of using an old 'previous generation' PC (which would have been more than capable of delivering the performance and functionality that I required), due to the inherent noise generated from the standard PC power supply, CPU and case fans - they're also too large and look pretty awful.
This lead me to look at the Mini-ITX form factor and associated cases. These are ideal for my requirements, low powered and silent (with most cases utilising an external power supply - like laptops).
Motherboard
Via EPIA CN10000G Fan-less C7 Mini-ITX
I opted for the Via CN10000 motherboard as it used the latest Via C7 low power processor, was fan-less and supported automatic power-on.
The power consumption of this motherboard is only 9W when idle!!!
Case
Travla C158 Mini-ITX Case with 90W PSU
This steel case includes an external 90w power supply and can easily accept the hardware I'd selected. (They also make a 60W version that would have been just as suitable, but was out of stock when I ordered).
The case measures 305mm (wide) x 65mm (high) x 270mm (deep).
A Compact Flash card reader is available as an optional extra, which might be useful if you plan to boot your system from flash memory (I'm not going to at this stage).
RAM
Corsair Value Select 1Gb DDR2-533 (PC2-4200)
(I believe) Linux when booted runs almost entirely out of RAM, so I opted to go for the maximum capacity the motherboard supports.
Tip - If you use a different case / motherboard combination, check if you require low profile ram as this is sometimes required due to the limited room.
Hard Drives
I've tried several different solutions for files storage, initially I used a single 3.5" HHD which I found too noisy. This is because the modern Linux file system (ext3) uses journaling (where the hard drive is accessed regularly) - this prevents the drive from ever spinning down when the system is idle. My current configuration has two separate drives, the first for the operating system and a second for file storage; there are significant benefits in this configurations.
I've compiled a page reviewing alternative drive solutions, see here.
The drive I've used for the operating system is a flash Solid State Drive (SSD) which is completely silent. (Previously I had used a 2.5" laptop HHD which was very quiet - but not silent).
The drive I've used for file storage is a conventional SATA 3.5" HHD from Samsung, this has been mounted as an 'ext2' file system (see here) that will allow the drive to be spun-down when its not in use (after 10 minutes of inactivity) using the 'hdparm' command (see here); therefore the drive is silent when not in use.
Other Stuff...
The only other part I required was an 44pin/40pin (3.5" to 2.5" drive) IDE adapter, obviously if you use only a 3.5" drive this won't be required. If you plan to use SATA drives you will need a SATA to Molex power adapter as the case doesn't support SATA power connections and a SATA data cable (I used a cable that combined the two).
CD/DVD ROM Drive
I'm not permanently fitting a CD/DVD ROM Drive as after installation of the operating system I'll have no use for it. During installation I temporarily connected a spare CD ROM to the second IDE socket on the motherboard.
It should be noted that if you chose to run a two disc configuration similar to mine, the CD/DVD media tray can be used to mount a 2.5" Drive (4 holes are provided), but this will prevent you permanently fitting a DVD/CD ROM.
Mini-ITX Server Build Pictures
Here's some pictures of the finished unit, note the 2.5" flash SSD attached to the removable CD/DVD ROM media tray (there where 4 mounting holes are provided).
There is a small 40mm case fan actually under the CD/DVD ROM media tray (quite what good it could do there as the RAM shields the processor from any draft it would create); I've left it disconnected for now as the system remains cool without it.
I was able to use full size RAM, there is about 2mm height clearance under the raised portion of the removable media tray.
If I'd had a motherboard with the RAM slot (3mm) further to the rear of the board it would have fouled with the main section of the removable media tray. You can get 'low profile' RAM - it would have to be at least 7mm shorter than the type I used (which was approximately 30mm high).