PALO ALTO, Calif. - Hewlett-Packard Co., a maker of personal computers, printers and servers, said Wednesday that Carly Fiorina has stepped down as chairman and chief executive officer, effective immediately. "While I regret the board and I have differences about how to execute HP's strategy, I respect their decision," said Fiorina in a press release. Hewlett-Packard shares closed Tuesday at $20.14 on the New York Stock Exchange (news - web sites), but rose $2.24, or 11 percent, to $22.61 in premarket activity. Robert P. Wayman, HP's chief financial officer, has been named interim chief executive officer and was appointed to...