Most of the posts highlight what I am focused on and express work and personal experience. Reason I put them here - recall later or help someone else with similar challenge.
I did not have much experience with 3.1, but this Windows 95 (Chicago) is the most rememberable graph UI'ed computer from my childhood (90's).
It's 2016 and I run my 2GHz OS X with SSD and 8Gb RAM while that old beast needs just 133 MHz (in 95th that was tactic frequency of my PC) and 128Mb of RAM with 1024 Mb of hard drive (just to install OS).
One of the problem what can occur here when trying to boot it first:
People talking about patches and hotfixes along with hyper threading and bios settings, but just slow down your processor and make it 5% or even less from what you have and you'll see the profit (it is VirtualBox setting for CPU). See below:
Starting Windows 95! ;-)