SWITCH HORSES: Roger Johnson, chairman of Irvine’s...

SWITCH HORSES: Roger Johnson, chairman of Irvine’s Western Digital Corp., is a longtime loyal Republican who enjoys showing off an extensive elephant collection at his office. But his frustration with George Bush--which first surfaced when he co-hosted a reception for Arkansas Gov. Bill Clinton last fall--has led him to the donkey. Johnson was among a group of U.S. business executives who endorsed Clinton Monday. . . . Johnson warned he would break from Bush if the President didn’t do more to boost the economy.