Windows 95 marks its 15-year anniversary this week. Reading through the online reminiscences, I realized I'd forgotten the sheer size of Microsoft's marketing blitz behind the operating system: the Empire State Building lit up in company's colors, the gazillion dollars reportedly shelled out for the Stones' "Start Me Up," and even a "cyber sitcom" starring Jennifer Aniston and Matthew Perry.

(I'd embed the YouTube clip for that last one, but I don't want to be responsible when its sheer mind-numbing awfulness drives you to leap from the nearest roof.)

Originally codenamed Chicago, Windows 95 introduced the Start menu, taskbar, and limited multimedia support. Its system requirements seem quaint in retrospect: PC with 386DX or higher processor (486 recommended), 4MB of memory, one 3.5-inch high-density floppy disk drive, VGA or higher screen resolution.

The operating system also developed into a platform for Microsoft's push onto the Internet--although Windows 95 didn't come bundled with Internet Explorer upon its initial release, the company included the browser with its Windows 95 Plus! Pack. The conjoining of Windows with Internet Explorer, of course, would eventually help trigger Microsoft's antitrust headache.

With those elements (and more) in place, Windows 95's interface was far more user-friendly than the clunkier Windows 3.1x, helping accelerate its adoption even without the $300 million marketing campaign.

Microsoft eventually declared Windows 95 obsolete in 2001. Even so, the operating system established the template for later Windows versions--including Windows 7, which Microsoft claims has sold 175 million licenses since its October 2009 release. The question is, having spent 15 years hewing so close to a certain model for its operating systems, where does Microsoft go from here? The cloud, and the attendant paradigm-shift, looms ever closer.