Microsoft won a $478 million, six-year contract to provide software to the U.S. Army, the biggest order ever for the company's programs. The agreement covers 494,000 desktop computers, Microsoft spokesman Keith Hodson said.

The Defense Department has questioned the security of Microsoft and rival products in the wake of the Sept. 11 terrorist attacks. One of the department's server computers was attacked in March using a flaw in Microsoft's Windows program. The contract shows the Army has decided that Microsoft's security is sufficient, said Rob Enderle, an analyst at Forrester Research.

Read more: The Seattle Times.