It's hard to believe that Windows is 30 years old this year. Originally a graphic shell that sat on MS-DOS, Windows has blossomed over the years to be the visually rich experience it is today. That's not to say it hasn't encountered a few pitfalls along the way -- Windows ME, anyone? -- but despite weathering rivals from the likes of Apple, Microsoft's pride and joy is still the most widely used personal computer operating system on the planet. In the gallery here, we take a look back at Windows through the ages. Be sure to keep an eye out for a few cameos from Jennifer Aniston, Jerry Seinfeld and, of course, Steve Ballmer.