Dear Simon:
--I see you have already made your choices, but I include the below which was written earlier, for everyone's perusal. I never know just what I am going to get into so I like to make my builds as adaptable as possible.
--I am currently also building a new computer. I have been doing research for a month or so. I do not play games, but I do run a lot of video programs simultaneously, so I have need of bandwidth, speed, reliability and redundancy. To keep the cost down I recommend an AMD CPU and Motherboard. The motherboard should be a full size ATX with 2 PCIE 2.0 Slots (so you can use 2 video cards if need be) and as many PCI slots as possible.
--The MB should have HDMI, AM3 Socket, at least 6 SATA 6GB/s jacks, at least a couple of USB 3.0 jacks, and be able to accept a max of at least 32 GB DDR3. You should buy 2 8GB 1600 MHz sticks to start with and more if needed. The Asus board below is a good example.
http://www.ebay.com/itm/ASUS-M4A88TD-V-EVO-USB3-AM3-AMD-880G-HDMI-ESATA-6Gb-s-DDR3-ATX-MOTHERBOARD-/251251746186?pt=Motherboards&hash=item3a7fc5658a--For mid level quality power supplies you cannot beat the OCZ 500 and 700 with the plug in wires for a clean, no hassle install. The CPU can be selected according to preference. The case should be a full tower with at least 5 external 5.25 bays. The case should have a flat top which you can stack things like the UPS and other things on. The extra bays in a full tower will allow you to install Addonics Hot Swap Racks for HD and SSD drives. I use the 2 bay Addonics Snap-In for SSDs, thereby allowing quick clone and switch. Once you use an SSD for boot up you will never go back.
--The rack setup allows you to clone exact copies of your important information frequently. After you clone the drive, you turn off the target drive, until it is needed again. This method unlike raid allows average drive usage to be reduced by half over RAID, which after a couple of years makes a real difference in cost. --I have had all kinds of problems with consumer level RAID and backup software and hardware. Many is the time I have been unable to restore a friend's computer that had regular backups made. Using the disk clone system with hot swap racks allows you to instantly check your backup, and provides certainty. You can even rotate cloned drives to a second location, or a fire & water proofed file cabinet or safe, to provide protection for all but the worst disasters.
--The above design can be used or reconfigured to do almost anything. With the disk clone and rack system, a home user can take the risk of used motherboard, memory, and case to save a lot of dough.
--Final note; I always keep at least two complete systems up and running at all times, because I cannot afford to be shut down for days. I also keep a couple of cheap Acer laptops in ready to roll condition at all times. Cops feel uncomfortable carrying less than 3 guns, and I am the same way with computers.
“If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.”
John von Neumann 1903 -1957
Best Regards
Clear Ether