Okay he sent me a PM asking for my thoughts on his post.

Parts compatibility aside, I agree with overkill. Definitely use Windows 7 (that goes for everyone, including those asking how the hell you get more than 7-10 fps in dalaran) with Aero disabled. I don't even have to look at the specs if you tell me you have 8 cores and 3 of (nearly) the fastest consumer video cards available, and will only be running 5 WoW characters. On the other hand, I don't think you will be disappointed if you build a PC like that (at least where the parts are compatible with each other), assuming the money isn't the problem. You will probably be afforded the opportunity to turn your graphics settings up, which is not something a typical 1-PC 5 boxer can do without sacrificing necessary performance.

I don't know what boards, if any, support dual i7, but the added "cores" from Hyper Threading will probably not measurably help you, when comparing dual Xeon vs dual i7. Hyper Threading does improve some specific circumstances, but I believe its benefits are best realized with fewer real cores. (I don't have benchmarks to back that statement up and I don't claim to be an expert on this particular subject, but it seems to me that the more actual cores available, the less useful the Hyper Threading's ability to "process another thread while one is waiting if the pipeline has room" will become by virtue of having real cores available that don't have the "pipeline has room" catch. I could also be exactly wrong on my guess)

You could get away with only using one video card (say, one 295 instead of 3 285s) if you didn't want to use all 6 monitors. I only use one myself, but it comes down to personal preference -- you're building what you'd like it to be, after all. RAM-wise, 18gb is way more than you need. To run 5 WoWs, a mere 8gb is more than enough, and 12gb gives you tons of breathing room for any applications that want to use gigabytes of RAM.

For power supply to power 3 video cards, Sajuuk's estimate is better than I would know to tell you. The PC Power turbo cool power supplies seem pretty reliable (I use a 1000W myself), and the 1200W is certified by nvidia for 3 video cards, so I imagine it would work. You do have to be careful about what PSU you get, it needs to have multiple 12V rails, and I guess some say they do but dont (Wikipedia: For a time, power supplies were marked and sold as having multiple +12V rails, although no current limit circuitry was included. As of 2008, having only an overall +12V current limit is seen as a desirable feature, and "single-rail" power supplies are advertised and sold as such, although it is still common to find power supplies for sale that falsely claim to have multiple +12V rails. - http://en.wikipedia.org/wiki/Power_supply_rail ) and you won't be very happy when your PC doesn't work because the PSU can't handle your hardware. Anyway, the suggested PSU should be fine.

As far as SSD and raid, my personal opinion is screw that. I'm pretty sure just using Windows 7 will improve performance enough that you'd probably be going through all that for not much of a reward. If you want performance, keep one installation of WoW -- use symlinks and/or Virtual Files via ISBoxer to achieve the other desired effects (keeping account name, server and character for login, etc). That should help performance by increasing cache use. You can still do your raid if you want, but I wouldn't do multiple folders if you want performance. I probably wouldn't bother with mirroring 6 drives though, maybe 2 or 3 but 6 is stretching it. I use a single 10000rpm SATA drive, and I don't think the hard drive is a big bottleneck for me at this point, considering the performance improvements in that area from switching to Windows 7. It only needs to load data from disk every so often, so generally the CPU, Video and RAM are the main offenders.

There's my thoughts, I'm not an expert when it comes to some of this hardware selection stuff, but I can program the shit out of them and tell you why things are happening wrong in many cases