There is no doubt that the main stream i7 Sandy Bridge can easily keep up with the older generation performance chips, i7-9xx.
But expansion capabilities on the Sandy Bridge platform are limited. If you need a raid controller, your video card will downscale to 50% of it's performance, if you need an AJA, BM or Matrox card, you are out of luck. If you need both, forget it.
If you can wait a couple of months, the new Sandy Bridge E is the one to wait for, together with the X79 platform. 40 PCIe-3.0 lanes versus 20 PCI-e-2.0 lanes, quad channel memory versus dual channel, hexa or even octa cores instead of quad cores, 15-20 MB L3 cache versus 8 MB L3, etc.
now behave... you can have both.. but again who needs an 8 drive raid array..
to the OP all the answers you need.. X58 = waste of cash unless doing lots of animation.
Core i7-990X Extreme Edition vs. Core i7-2600K. (page 1 to 13)
What it all means is that the LGA 1366 flagship i7-990X does perform slightly faster in PR (Premiere Pro) CS5.x than the LGA 1155 flagship i7-2600K - but nowhere near three times faster. What's "extreme" about the i7-990X is the price: It costs more than three times higher than the i7-2600K.
And as I have noticed with the higher-scoring quad-core i7-9xx systems in the PPBM5 list, they all use expensive, high-end motherboards that more than offset the cost advantage of the i7-9xx quad-core CPU over its i7-2600K competitor: The typical LGA 1155 motherboard in the higher-scoring i7-2600K systems costs about $180 to $190 while the motherboards in the higher-rated i7-9xx systems almost always cost well over $300. None of the quad-core i7-9xx systems based on lower-end LGA 1366 mobos (priced at less than $250 for the motherboard) ranked higher than about 43rd out of the well over 400 systems on the PPBM5 results list.