Eric Siebert at Virtual Strategy Magazine has a nice write up titled Top 10 things you must read about processors (CPUs) and virtualization
The CPU is the heart of an ESX host server as it provides the processing muscle for all the virtual machines competing for this valuable resource. Therefore it is important to know how physical processors compare to virtual processors and how CPU scheduling occurs on an ESX host. It’s also important to understand the new processor virtualization technologies from both Intel and AMD that offer many benefits to virtualized workloads. The items on this list include documents that cover how the CPU scheduler works, when to use virtual SMP, choosing between Intel and AMD processors and white papers from Intel and AMD describing their new processor virtualization technologies.
Lots of reading here all, it will does us all some good, my included.