Get a Norco rpc-4020 or 4220 or any cheap case that can hold the drives you want to use and more, more or less any cheap dual- or quad-core cpu (my server is still running an i3-2100 and never breaks a sweat) then however many hardrives you want to start with. I run whs2011 (our house is more or less exclusively windows so whs integrates super nicely and backs up each client every night) with Stablebit Drivepool and PerfectDisk's defragger for whs.
Stablebit Drivepool is a type of software raid. I have used this for over 1.5 years and not had any issues I have added and removed drives several time to enlarge and one time to replace a failed drive and not lost any data. With the Drive pool you can tell it to mirror everything onto a different drive and then you have redundancy. This is easy to use and like I said it integrates super easy with all your windows PC's. I also have apps or programs installed that allow me to push media out to my ipads.
At the present time I am building a new server using windows 2012 essentials. but I have been very pleased with the Windows Home Server 2011 and it is just 59 dollars for this software.
Just my 2
the reason I have not used one of the free NAS programs is the learning curve not that I mind learning but then I would also have to teach my wife and kids about this. with the WHS I have not had to do this and what I have showed them is easy and like windows anyway. I work in Indonesia for 1 month and then home for 1 month so up time and ease of use is very important to me.
also if you want to serve movies and media you can install My Movies on it and this works awesome to me. it uses windows media player to play movies, music and photos also. you can get more info on this at http://www.mymovies.dk/
Also if you want more information on windows home server go to this site and read or buy one of the books on using it. it tells you how to do pretty much everything you want to do and more in a simple and easy to read and understand format. http://www.wegotserved.com/Edited by seross69 - 9/25/13 at 3:02pm