If it is for "Serious server operation"...
...you should get ESXi (which is free when you don't use vcenter) and run everything from there, You'll need vsphere client (runs only on Windows) but that's all.
Virtualization on top of some other OS is not for REAL serious operation, only bare metal hypervisors delivers. I'am runnin 7 OpenSuSE based servers and an Win 7 (for admin) on an old HP Proliant DL385 (Dual Core Opteron) for fun... oh yes, I run VMware vsphere for profit too. If you only run on 1 server you don't need the cool features anyway.