I realize that if you're a twentysomething today that IBM almost does't mean anything -- but back in the 80s they really opened the door to the PC industry. And what's amazing is that they're an old guard company that really embraced a disruptive technology -- something that a company like DEC tried, but failed at. By the way if you're interested in the story of how the IMB PC got started this is a nice starting point:
http://en.wikipedia.org/wiki/IBM_Personal_Computer#Origins