Hi,
no problem.
My argument against was purely technocratic. Since it's technically not possible to build 2P with it, and even for the prices of used components here, they're too old to give relative comparative performance.
And than again, 1366 models will not server you for long, esp. with 4Ghz overclock, they will probably finish their lifetime in year or two since you will buy it.
Regarding Xeon W5580, yes that is possible. It can't be overclocked, so you can take directly the 3.2Ghz Passmark score, which is 4760. Benchmarks can be found on
http://www.cpubenchmark.net/ . It's very reliable and transfers well to rendering speed.
So the 2P performance will roughly double (or 90+ perc.), so we can count roughly 9000. Modern middle class Haswell CPU like i7 4790 has score of 10 000 non-clocked, and can be clocked additional 30perc. very easily, so it would give you about 50perc. more speed in rendering, and about 150perc. more in single-threaded tasks (modeling, viewport, photoshop,etc...)
I understand your bad country situation and I offer a lot of sympathy for your side of your conflict. I can wish you that it will be better, but I don't really believe it sadly.
I don't come from particularly rich country either and I don't have wealthy background behind me. Solution for my career was to always work outside, 70perc. of my clients don't even know where I am from, and if they do, they don't know where it is.
We do have a benchmark thread in general section, but it's bit outdated (Based on old Alpha4 core, 2+ years old), so it's not very reliable if you want to compare Xeon processor. But for general i7 and such, it's good.
Older HW often seems like great deal, but the performance increase, even though very little in last 3 generations (Starting with SandyBridge), is quite big when you compared it to Nehalem based gen (like the Nehalem-Bloomfield i7 9xx/W5580/etc..).
But the price often isn't that lower and is quite proportional to what they perfom at. So even if you're able to buy such machine for 300 euro, a modern Haswell one for 600 euro will be twice as fast (even i5).
When the budget is little, I suggest to buy low-middle class but recent CPUs. i7 4770k/4790k, 16GB of ram, 550W 80+ Bronze PSU,etc... something relatively cheap (<900 euro), but still much better than old 1366 CPUs.
With computers, it's rarely possible to get the benefit you get like with old cars.
