Photos: Bill Gates at RSA

Craig Mundie (left), chief research and strategy officer at Microsoft, and Bill Gates (right), chairman of the software maker, take the stage at the RSA 2007 conference in San Francisco on February 6, 2007.

The executives said that Microsoft had made great leaps in securing its customers' use of technology, but added that the increasing use of Net-connected devices meant more challenges lie ahead.

The keynote speech comes nearly five years after Gates sent out a memo stating that Microsoft's focus would be on security, or "Trustworthy Computing."