Best affordable Intel CPU to buy for your personal virtualization project, Core i7 2600, not the 2600K!
1) Virtualization of many concurrent operating systems is better able to feed the CPU a lot of parallel threads of execution, better leveraging the hyperthreading the Core i7 offers than a single operating system, making this approximately $300 investment well worth it. Much more about this rationale at datacenteroverlords.com. Find all the CPU speeds and feeds at anandtech.com and intel.com .
2) The Gamer oriented, better-for-overclocking 2600K is a great CPU for about the same price, but it won't allow VMDirectPath! Ouch!
Imagine you wish to pass USB 3.0 through to a Windows Virtual Machine (say for offsite backups to external USB 3.0 drive for a Windows Home Server VM, for example), or thinking a little further ahead, perhaps a Thunderbolt (LightPeak) card someday, where you specify the device to pass thru in ESXi 5.0, and then you assign a particular VM to that device, installing drivers in that VM accordingly. And you probably want a CPU/motherboard combo that has built in video, since you don't need a watt-wasting discreet GPU for VMs.
Read much more detail, and see tested, known-good-configs documented in the article entitled:
"Z68 Sandybridge Motherboard VT-d Test Matrix: Which Mobo/CPU combo works with VMware ESXi 4.1U1 VMDirectPath feature?"
found here: tinkertry.com/vmdirectpath