Don’t know which private fax numbers Barry Diller, the peripatetic former (and now unemployed) chairman and CEO of Fox Inc., keeps stored on his hard drive. Do know that wherever Diller goes, his seven-pound computer goes too. ”It’s helped me be curious again…,” he says cryptically of his top-of-the-line, $3,900 Apple PowerBook 170. And will the mobile mogul machine be linked permanently somewhere soon? That’s as big a secret as his password.