I have added this post for anyone who might be interested in a small box.
I have a fixed ip address with my broardband and could not see the point of paying for hosting my web sites or for my site development space.
so I built a small server.
First of all you have to think of what you are going to do with the appliance, and where you are going to use it.
I have built a small server for a few websites, nas box and mail server.
Hardware most from EBay (Can be a risk but bid low to avoid big losses)
Case : small ITX
Cpu : Celeron D 3.2 Ghz
Main Board : Zotac NForce 610i-ITX (bought new from computer supplier)
Ram : 2 Gigs DDR2 800
Aditional Cards : SATA Compact Flash Reader
Storage : 16 GB Compact Flash Card (For the OS)
1 TB SATA Harddrive for Non OS data.
1 DVD Writer For installing and Burning Backups etc.
The most expensive item out of the list was the main 1 TB harddrive.
Once the system was installed I noticed that it took longer for the bios to post boot than the Server to load wich is around 15 seconds.
There is also one advantage of using ITX
Low power mine runs on a 250 watt psu, also if the case you purchase has no room for a conventional psu you will have to purchase an external unit with the module that connects to the main board and disc drives.
This is not such a bad thing as with an external psu you have the potential to add a battery pack inline as a ups. The only complications with this is that a higher current psu would be needed around 1Amp higher than needed for conventional connection to PC. This is for trickle charging the batteries. Also a few extra plugs and sockets and some electronic components for the charging circuit. If you live in the right area you can also go green and use solar power to run your server.
Now this Is Going to the extream but the external psu that run most of these small Itx systems is 12 Volts which happens to be the same as the router and the cable or dsl modems.
as long as you calculate the total current used for all 12 volt devices one could run the server, router and modem off the Psu, battery backup and solar system.
Lets not forget you can also get small wind generators.