Middle Between 3930K and Z820

[Morne]

Hi all

I'm busy looking at various systems for a proposal. I need a bottom, middle and high end system for workstations.

For my "bottom" system I'm going for nothing less than a custom self built i7 3930K with 32GB Ram and GTX 580 with all the things that goes with that like MOBO, case, SSD etc
For my "high" end system I'm going for something like the HP Z820 that Bertrand and Peter just got themselves.

So with the bottom and high pretty much sorted, what would be a good system for a "middle" in between these systems? Any recommendations?
Self built or branded doesnt matter, I just need something in between

[Morne]

Do you get a mobo that can take 2 X 3930's?
maybe that could be a good "middle" range workstation

otherwise possibly someting with just 1 XEON, but that XEON has more cores or clock speed than the 3930?