Ever wanted to know what Windows looked like back in 1985 (or just wanted to refresh your memory)? Well, now you can run it in a browser. Other browser-based OS emulators include Mac OS System 7 (1991), Windows 3.1 (1992), Mac OS 8.6 (1999), and even Windows 95.
It’s interesting to see how things have changed over the years, particularly with the difference between 95 and Windows 7 (the last Windows that kept the same basic appearance), or between OS X 10.2 and the current 10.9. No huge jumps, just little steps, taking and removing things until we’ve got the OSes we’re used to seeing today.
Also: if you’re reading this and still running Windows XP? Please don’t. Get something else, anything else, right now. (Ubuntu‘s quite nice, for example. And free!)