4 cores is great if you're opening most newer games, and you have basically nothing running in the background outside of the basic obvious stuff that would be running in the background anyway, like anti-virus.
Some few games already show an increased performance with 6 cores over 4, and we should probably expect that in the coming years this will become increasingly more common.
Also, I see someone who is dabbling with VMs as something of a power user. You're not someone restrained by some kind of lack of computer knowledge. You probably explore and self-teach.
And you should probably aim for 6 to 8 cores if you're running your game and doing almost anything else in the background: FRAPS or equivalent (video recording), some kind of file conversion (music, video), streaming, watching videos/movies on a 2nd screen or listening to videos in the background, several-tab browsing, etc. Even if you don't do these tasks regularly, it's really nice to have the extra processing power to push through it without any real hiccups.
I've used an OC'd 3960x since early 2012 (6 cores) and I can honestly say that it was probably the best overall computer purchase I will have ever made when you consider how long it stayed both relevant and snappy doing anything I ever threw at it. I'm only now looking at a possible upgrade 6 years later, and even then, I may hold off another year.