We mentioned what a media server is, now lets talk about what components are needed to build one.
Unlike an HTPC a media server doesn't need a lot of fancy components. Pretty much you need storage, storage, and more storage. CPU, graphics, ram... all are minor requirements. Pretty much whatever minimum requirements the OS calls for is all thats needed. This pretty much holds true with one exception- If you have to transcode your files on the fly then you will want a bit beefier CPU. I went with an AMD dual core 3Ghz processor. I won't need that much power, but it wasn't expensive so I said why not?
I personally do not want any degradation of video/audio so everything on my drives are uncompressed and in the native file format it was on disc. The nice thing is these files are natively supported by my PS3 and the O!Play so no transcoding is needed... just streaming bandwidth.
Which brings us to the one thing that is crucial, your network connection. Many people try it... some say it works for them... but the one thing you want to stay away from, and that isn't a friend of media servers and streaming is wifi. You may be able to use it for standard def, or even AVCHD files or M2TS files from a Hauppauge PVR-1212, but when you start getting to true HD content, sooner or later there will be stuttering and drop outs.
Do you need Gigabit ethernet? Depends.
Some will say no matter what you need Gigabit, however if you're only streaming to one or two end units at a time then 100baseT should be more than enough bandwidth even for Bluray streaming. Of course if you are running your network cable now as part of your welcome to the 21st Century home renovation project... might as well go with Gigabit. Why not? If you already have your house wired for 100baseT I wouldn't sweat it. Just don't plan on streaming 40GB Bluray files to every HDTV in your house!
Now for the number one biggest component NOT TO SKIMP ON- The Power Supply.
The more drives you intend on running, the bigger PS you'll need. A 750W PS is the minimum I'd use for a 20 drive server. I actually went with an 850W PS.
Here are the invoices for the components I purchased. As I mentioned, this doesn't count the drives. I already had 8TB and did buy four 1.5TB drives. The reason why I am not including drives in the cost is this will be up to the user on how many, what size and besides, you can add them as you need them.
I ordered from various companies. Initially my urge was to try and order everything from one place to save on shipping as well as have minimal packages I had to wait on. In the end I found certain items were significantly lower at different online stores. If you can get your favorite store to price match that would be great!
Here is my NewEgg order.

Right off the bat it's pretty easy to see the big ticket item on that shopping list is the Norco RPC-4020. For those that don't need 20 drives, or need hot swappable drives, I recommend the
Norco RPC-450B. This is a really nice case for $79 that has room for 11 drives, and you can even convert the case to hot-swappable drives.
A lot of people are jumping on the newer model 20 drive case, the RPC-4220 but do some planning before you jump head first. The 4220 is a whopping 19" wide whereas the 4020 is 16.9" wide. I was just about to pull the trigger on the 4220 until I measured my rack, which is 18" wide! No dice on jamming a 4220 in there. Functionally the 4020 and 4220 are the same... they both are ginormous computer cases that will hold 20 drives.
[MOUSE]Update: I spoke to NorcoTek. Someone told me both the 4220 and the 4020 are the same size. It's not that I didn't believe him, however the spec sheets did call out different dimensions, plus the guy that was reporting the sizes were the same also referenced the RPC-4224, Which doesn't exist. So the best way to find out the facts is to call the source

[/MOUSE]
If anyone is looking based on size, these cases are indeed the same size. There are a lot of updates to the 4220 however there is one change that could have a bearing on whether someone gets the 4020 or the 4220. The 4220 uses a 2.5 inch system drive over a regular sized 3.5 inch drive. No biggy, but to some that have a 3.5 drive they planned on using they will have to buy a different drive.
So how big is this puppy? For size perspective that's a normal size PC case compared to the box the 4020 shipped in. The three coconuts are my son and two of my grandsons.
The first thing you'll notice after the size is the packing. It comes double boxed and nestled safely in Styrofoam. It weighs in at 38lbs and when I say it's big... and as you can see from the first picture... when it arrived my wife yelled upstairs and told me my refrigerator showed up!
Below is a shot of all the drive bays popped out. This seems to be a mandatory gratuitous shot
Here is a shot of the case with the top off and the system drive and slimline DVD drive mounted. Below them is where the 20 hot swappable drives reside. The area to the back is for the PS and motherboard. As it can be seen there is more than enough room inside for any board you want to throw in there.
And another shot giving some size perspective-

Also on this order was the motherboard, CPU and Ram. This is a killer motherboard and really is overkill for a media server. In fact this motherboard could function for an entry level HTPC build! Why did I get it then when I said we don't need a bunch of fancy and expensive components? Well for this particular setup you need a SATA port multiplier since no motherboards out there come with 20 SATA II connectors. It just happens that the interface cards I went with needs PCI-E x4 slots. You can also use PCI Express x16 slots.
Next is the invoice from my TigerDirect order-

At the time I placed my order they had a slightly better price for Widows Home Server, and the 120mm fans were significantly less than they were on Newegg. Also I thought they had better prices on Power Supplies.
And the last invoice is from SuperBiiz

SuperBiiz had the best prices on the Supermicro AOC-SASLP-MV8 Sata port multiplier cards. They also smoked everyone on the SFF-8087 to Discrete Forward Breakout Cables.
If you get these cards be careful on what cables you get because the reverse breakout cables look the same in the pictures but they won't work.
So really the expensive items for me were the case and the port multiplier cards. I showed one alternative case, and there are many options out there if you don't need 20 drives. As far as port multipliers, there really aren't that many options out there. Addonics does have a
5X1 Internal SATA Port Multiplier (PM) for $69, however I haven't used one of these before and haven't read any reviews of anyone that has used one.
That's about it as far as the components. Oh... I'm sure people have noticed all those fans I bought... Well they were .99¢ each when you buy a lot of 10 so I said why not. I will always need a fan for future builds.
I'll take plenty of pictures when I go through my build.