There is no doubt that the i7-970 hexa core is a great CPU. OTOH, it carrries a price tag of around three time the i7-950, but does not triple the perfomance. Sure it is faster, but not that much and your material, XDCAM-EX is not as taxing for the CPU as AVCHD is.
An alternative might be to get an i7-950, but increase your memory to 24 GB. The added memory will make up the performance penalty of only a quad core versus a hexa core. This is especially true with your workflow, scaling down to DVD on export. There the extra memory will come in quite handy for good rendering and export times.
I see your OS disk (SSD), I see your 2 x 600 R0 scratch disks, but where are your media and project drives?
Just guessing here, but if you need 1.2 TB for scratch, I assume you need quite a bit of storage for your media and projects. Have you considered a raid3/5 array for your media and what controller do you have in mind?
What CPU cooler and what PSU do you have in mind?
Have you looked at the PPBM5 Benchmark
It shows you that 19 out of the top 20 systems use raids.
Thanks for your detailed reply. I forwarded your comments to my builder. I am showing the Coolermaster HAF912 with 700W Coolermaster Extreme
Are you saying that I should go with smaller scratch drives and that I should add an internal drive for storage?
Not necessarily smaller scratch disks but adding at least two extra drives would be benficial.
I've not looked up the HAF912, but a popular choice here is the full tower HAF932. The PSU might be a bit low in output. Once you have the details of your system worked out, go to eXtreme Power Supply Calculator Pro v2.5 and get the Pro version. Then enter your components, set CPU load to 100% and capacitor aging to 30%, add 10 - 15% for safety and you know the PSU requirements.