Most of you here won't remember this, but back in the olden days there was once a version of Windows called 3.1. It was unstable, plain-looking, clunky, virtually feature free, and we liked it. Want to know what it was like without actually loading it up on a real PC? Just go to this website, and there it is in all (well, some of) its glory:
http://www.michaelv.org
It's a clever creation by a programer called Michael Vincent, using JavaScript to let you operate a replica of Windows 3.1 that feels remarkably like the real thing. You can even fire up MS DOS and type in a few choice commands that actually work. Heck, it's even slow like computers were back then.
Source: http://www.crunchgear.com/2010/01/24/run-windows-3-1-in-your-browser/