Does ESX installable requires 2 physical processors or would one dual core work?

I would like to install ESX 3i on a dual core Desktop.  WOuld this work or does ESX require two Physical Processors?   The requirements state 2 CPUS but im not sure if they consider 2 cores to be two CPUs.    I've only done installs on servers with multiple CPUs.....want to know the answer to this before purchase the components for this desktop i plan to build.

Thanks