Depends on what kind of virtualization you would be doing, though the type I'm wanting is host/guest and not hypervisor/guest/guest which in theory would be just as fast as having two machines running the same hardware. The cpu and ram would be plenty because let's be honest linux is nice and lightweight, and some very simple games, like ftl, and terraria work great, granted they also have linux versions that I would rather use. Really the only thing that is lacking from the virtual machine is good access to the graphics card, which is what I'm hoping to find a way to get around right now.
as far as proof that running windows in certain virtual environments doesn't slow down game performance I will reference you to this video--
with these bench marks-- http://www.3dmark.com/3dm/5992909