SP 2010 Sizing VMware

Hi 

I am new to sizing and virtualization. So trying to understand it more.

As I understand there are two options to virtualize SP 2010 a) Hyper V b) VM ware

I have used HP Sizer or similar tools for sizing physical farms. I am also aware of option available iN HP sizer for sizing HYper V virtualization. But If I want to have virtualization using Vmwar etools then how shd I do and what parameters I need to take care?

Thanks