I originally assembled this computer about a month ago with two GTX 670 FTW+ video cards, but discovered they don't provide the best video rendering power, and SLI doesn't make a difference at all in Sony Vegas 12. In fact, they were only marginally faster at rendering than using the CPU alone, so I returned them. I am now going to try a few different video cards. If you have recommendations that would be helpful.
I also discovered that RAID-0 isn't as cut and dry as one would expect.
Running two SSD's in RAID-0 using the SATA 3 ports on the motherboard provided the best performance. Running 4 SSD's using the SATA 2 ports on the motherboard was about a 25% performance hit even with twice as many drives - that surprised me. Finally, using an LSI Logic HBA RAID card was the WORST in terms of performance, even though it was a SATA 3 card designed for RAID. (I returned that and will be trying an Areca HBA next)
The Velociraptor provides about twice the speed as a regular WD Black HDD, so that is nice.
Here is a complete gallery, which includes my old PC (which my wife was using), her new machine, and this one with before/after pics with the GTX's and RAID HBA.
Finally, I paid nowhere near the prices PCPP has listed. I got the CPU for $169, for example, and tried to pick up everything on sale using CamelCamelCamel alerts.