I would have bought the old octo 2.8 version if it would have been substantially cheaper over here compared to the 2.26Nehalem. The price difference between the 2 was under 500euros.
If I would have put in a larger drive in the 2.8, more memory and a larger video card (to get the spec's to about the same as the 2.26Nehalem) the price difference would have been virtually nothing. This is why I eventually opted for the newer architecture. Now just praying 10.6 will help with using more cores or that the new 64bit CS5 won't be too long.
I think you will be pleased with eather machine, I know I would even though the word satisfied doesn't seem to exist in my vocabulary when it comes to processing power