COSTA MESA, Calif., Dec. 11 -- Emulex announced that it will pay $645 million to acquire Giganet, a maker of computer circuitry cards that connect network attached storage devices based in Concord, Mass. Emulex, a designer of equipment that speeds data transmission, uses products that required fiber channel technology, which is used in storage area networks. Emulex will take a noncash charge of $10 million against earnings in the third quarter ending April 1 as a result of the transaction.