Xeon, Opteron, i7 & Skulltrail

Here at my work we are looking at replacing one of ourworkstations...this machine would be used for large assemblies,rendering, and FEA.

With the concept that money isn't really an issue in choosing a pcwhat way would you go...Keep in mind that this company expectstheir workstations to last 4 to 5 years in the engineeringdepartment and another 4 years on the shop floor afterward.
Assuming we went with the fastest cpu/ram offered, which would youchoose for the tasks above and why?

Dual cpu Xeon
Dual cpu Opteron
Single cpu Core i7
Dual cpu Skulltrail Core 2 Extreme Quad


Or the yet unreleased Xeon chip that uses the core i7 architecture?Supposedly coming out early this year.
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