Computer users are increasingly at risk of being lured to Web sites that surreptitiously download malicious software onto their machines, but stolen or lost laptops still represent most of the security breaches reported, according to a new Microsoft report.

Exploits, malicious software, and hacking accounted for 13 percent of all security breach notifications recorded in the second half of last year, while 57 percent of the breaches publicly disclosed involved lost or stolen equipment, the latest six-month Microsoft Security Intelligence Report says.

Computer users are advised to apply software updates regularly, enable a firewall on their system, and install and maintain antivirus and antispyware programs.