Personal Digital Assistants (PDAs) have become one of the important tools in our life. Their popularity are due to their small size and mobility which enable them to be carried anywhere. Along with their popularity, handheld devices are starting to become the target for the attackers, who are mainly interested in gaining the data stored in handheld de-vices. Therefore, security of handheld devices have attracted a lot of attention in an effort to protect the sensitive information stored in handheld devices. Securing handheld de-vices is a daunting task. It requires a careful design since the devices have very limited computational power and battery life. In this paper, we aim to review the security threats to handheld computers and propose several possible solutions. We performed some experiments to test our proposed solution in an iPaq Pocket PC.