workstation for comsol

Hello,

i plan on buying a new workstation for COMSOL 5.0. Area of research would be mostly acoustics in general with a wide range of different studies and up to sth like 10M DOFs. Its only possible to buy a workstation by our contract partner DELL, so i played a little with their configuration system. What do you think about it?

Configuration 1:
- Single Xeon E5-2667 v3 (8 cores, 3.2 GHz)
- 64 GB RAM (8x8), 2133 MHz,DDR4,ECC
- Windows 7 professional
- Nvidia Quadro NVS 315, 1GB
- 4 TB Harddisk, Raid 1
For approx. 3974 €

Configuration 2:
- Dual Xeon E5-2637 v3 (4 cores x 2, 3.5 GHz)
- 64 GB RAM (8x8), 2133 MHz,DDR4,ECC
- Windows 7 professional
- Nvidia Quadro NVS 315, 1GB
- 4 TB Harddisk, Raid 1
For approx. 3708 €
The same total number of cores, but dual CPU and with more performance per core (3.5 GHz vs 3.2 GHz)

Configuration 3:
- Dual Xeon E5-2650 v3 (10 cores x 2, 2.3 GHz)
- 128 GB RAM (8x16), 2133 MHz,DDR4,ECC
- Windows 7 professional
- Nvidia Quadro NVS 315, 1GB
- 4 TB Harddisk, Raid 1
For approx. 4759 €
Total number of cores is 20, but only 2.3 GHz and more RAM.

So basically what is more important? Number of cores or performance.
I have a CPU locked License, this should also run on a Dual CPU workstation right?

Also: Would it be necessary or wise to run Linux on this system? Id prefer to avoid it if possible, since my knowledge about it is limited.

Thanks for your input!