CUPERTINO, Calif. (Reuters) - Hewlett-Packard Co. said Tuesday that preliminary estimates showed shareholders had approved its purchase of Compaq Computer Corp., a result unconfirmed by voting officials. HP said its view is based on a preliminary estimate by its proxy solicitor. Voting officials are expected to take days or weeks to tally the ballots on the $21 billion merger that has been the subject of intense debate. HP shareholders met on Tuesday morning. In a statement, Chief Executive Carly Fiorina described the merger as winning a "decisive majority" of shareholder votes. That differed from Walter Hewlett, the dissident shareholder, who...