Ok, I take back my clock for clock thing. I remember reading that article, and saw the 3000+ vs 3000+ thing and forgot the the clock speeds were different. But that being said, the numbers mean the same thing. A 3000+ Winny or Venice will perform at about the same rate as a 3000+ Newcastle. Obviously, the Venice or Winny will do a little better, but the performance increase isn't noticable. Dual channel also does not provide a significant performance boost.
Yes, on memory benchmarks, you will see a huge difference, but in terms of real life performance, the increase is marginal.
Finally, the pci-e and pci comparison isn't a good one. Pci-e totally outstrips pci in terms of bandwith and performance. 939 does not kill 754 in terms of performance the way pci-e does with pci. So, your analogy was flawed.