A popular PC-maker of the '90s and early 2000s, Dell has had its head in the sand over the past five years as laptops and desktops stopped growing. Like other PC makers, Dell was blindsided by the popularity of the iPhone, iPad and Android-based smartphones and tablets. It has tried and failed to release successful smartphones and tablets. Now CEO Michael Dell is in an uphill battle to take the company private as it tries to extend beyond PCs to big data and cloud computing. But Dell's best days are likely over.