I'm new here, but I've been reading the site for a while. (A few months?) Let me start by saying this site is awesome! It's amazing to see such a detailed walkthrough and support of exactly what I wanted to do before I found the site at all, and after reading I've only gotten more excited about my soon-to-be media server. I'm sure my plans wouldn't be this streamlined without the help I found here!
I've got a background in electronics/programming, but I've never actually built a computer before. I'm planning on building two soon, a media server and a gaming desktop, so I'm starting with the media server since the parts are cheaper, so if I break anything, it costs less to replace. But I want to make sure I'm not doomed before I start because I've made a simple compatibility/design decision when choosing the parts. I've got an overall budget of about 1500 euro for both computers. (despite buying in GBP, grr) It would be awesome if anyone could tell me if I've done something stupid (or have missed something out) in my following part selection:
Case: The NZXT Gamma Case. 6 drive bays, as explained below.
Motherboard: Gigabyte GA-880GMA-USB3 AMD 880G AM3+ Motherboard I went with a motherboard with onboard graphics so I wouldn't need a graphics card for the initial setup and such when I'm first installing everything. I went for 6 SATA III ports, even though I only plan to start with 4 HDDs, to leave room to expand later.
Processor: AMD Athlon II X2 245e Energy Efficient Dual Core CPU My motherboard meant I needed to use an AMD CPU, which was good fun because I've only ever used Intel before, so AMD's numbering systems/product lines were a complete mystery to me. I thought this one was a pretty good idea since energy efficiency is important, but its specs still seem to be quite good. I was also considering the AMD CPU Phenom II 555 Black Edition Dual Core Processor but it seemed a little overkill. (And more expensive)
Hard Disk: 4x 1TB Western Digital Caviar Green Hard Drive. As advised here, I'm going for Caviar Green for energy saving, and because WD is a good manufacturer. And I've got a lot of media, hence 4 drives. I plan to use flexRAID unless anyone would advise otherwise?
RAM: 2x Corsair Memory XMS3 4GB DDR3 1333 Mhz CAS 9 Dual Channel I was slightly confused by XMS3 and non-XMS3 Corsair RAM, which didn't seem to be explained anywhere I looked. There were two sets of RAM where the 'presence' of XMS3 was the only difference, so any advice here would be great.
PSU: Antec BP550PLUS Basiq Plus 550W Modular Power Supply As far as I can tell, a 550W PSU should leave some headroom for upgrades in the future, given my current setup? Keeping up with the 6 SATA connections on the motherboard, and 6 drive bays in the case, this has 6 SATA power connectors.
DVD Drive: SATA DVDRW IHAS122-18 LiteOn I've just realized I probably need a DVD drive in here. I'll put a blu-ray drive in my desktop, because I have quite a few HD movies, but more for loading software and stuff. But this does use up a SATA port. Would people advise using an external DVD (USB) drive instead? (I already have one of those.)
Network Switch: 8 Port Edimax ES-5800G 10/100/1000 Ethernet Gigabit Environmental Friendly Switch I plan to link up all my devices via this switch, using gigabit cables so I get good enough transfer speeds for HD video. (Incidentally, I did a test earlier this year of video over Wi-Fi and it was quite unsuccessful, couldn't even get SD video playing without skipping.)
Also, I've only ever used laptops before, so I don't actually have a monitor in my house. With this in mind, I'm buying the monitor I intend to use with my gaming desktop at the same time as my media server parts, so I can use it to do the first set up for the server. It will run headless after that.
Monitor: Viewsonic 24" VX2439WM LCD Monitor A nice large screen, with speakers until I decide to get a proper sound system. (Depending on if I move house, currently the bass speaker would kill my neighbors.) And the line-out was important so I could plug in my Sennheiser headphones. I notice that it doesn't support HDCP though, could that be a problem in the future?
There are some other things I gather I need to pick up:
HDMI cable: so I can use the monitor (I'm amazed at how cheap these have gotten)
Cable ties: keep the case organized
Keyboard: I have a spare USB keyboard already
Mouse: If I really need one, I can borrow the mouse off my laptop for a few hours (USB as well)
Questions:
Do I need to buy thermal paste? (Or will it come with the CPU?)
Is SATA III worth the improvement over SATA II in practice? I saw a lot of SATA II drives and boards when I was browsing. Changing my mind about this would require rechoosing a decent chunk of the parts though, and future-proofing is always useful. (I looked at SSDs, but they're way too expensive for the media server, maybe a small one for the OS drive in the gaming desktop.)
Should I go with a case with more fans?
This may seem really stupid, but does the PSU come with the power cable that goes to the wall outlet, or do I buy that separately?
Am I missing any other cables?
And where would be best to get a static wrist-band?
Thanks all for your help!
), my thoughts are that the Intel Pentium P4 with HyperThreding was a long away ahead of anything AMD produced at the time. AMD don't seem to have really caught up, this is only my opinion so please any AMD fans out there don't flame me. 
I'll try to come on here when I've finished the build, or while I'm working on it, and let you know how it worked.