While about 6 percent of U.S. households have a personal data assistant or PDA, according to Forrester Research, thanks to technology advances in the handhelds, especially wireless connection to the Internet, the use of handhelds in business is growing strongly. Sales of handhelds are expected to gain 30 percent annually through 2005, says the Aberdeen Group research firm. About 8.9 million handhelds were sold in 2000. Among emerging features for security directors: wireless Internet allows users to receive alarm messages while some advanced units may soon be able to receive video surveillance images.