How did this happen? Apple is said to be about to announce a tablet computer by the end of this month. Microsoft will reportedly announce a tablet computer Wednesday night. Apple is run by Steve Jobs. Microsoft is run by another Steve, Steve Ballmer. Aside from that, however, the two companies couldn't be more different. Over the past 10 years, Apple shares have risen more than 700% under Jobs. It dominates the market for digital music players and has routed Microsoft in the smart phone market. Microsoft shares, by contrast, have fallen nearly 50% since Ballmer became Microsoft's Chief in January 2000. And while it has a toe-hold in the digital living room -- thanks to the XBox -- it has struggled to do what Apple has done so adroitly: master the consumer electronics market.