I am looking at purchasing an Imac (2011 21.5-inch: 2.7GHz). I have an aging windows 7 machine that I want to replace. However, I have tons of software and settings that I would like to keep as is. I'm would like to convert my win 7 pc into a VM. If I do this and run it inside of virtualbox or vmware on a new imac, what is the performance going to be like? Will it slow the imac down to a crawl? Im pretty sure it would choke my unibody macbook to death if I tried the same thing on it.