Congrats on the new hardware!
Just my $0.02, I think the recommendations of Stanford should generally be followed. When they made the last changes to the BigAdv program, the baseline was 16 physical cores. Through overclocking and HyperThreading, you may get by on 12 threads, but it is discouraged on the Stanford site:
Running a FAH Client on hardware that will only marginally meet the WU's Timeout is strongly discouraged. For example, it is not recommended to run bigadv (BA) work units on slower systems or systems with less than 16 cores and it is not recommended to run SMP work units on slower 2-core systems.
VM was common a few years ago, but with the Intel Core series it was a pointless option. I haven't been around the forums enough lately to know if it has any benefit now.