Personal computing devices which can connect to the Internet are subject to a number of security threats. These threats stern from two main sources - the ability for unsolicited messages with active content to be sent to the device from entities unknown to the user, and the ability for the functionality of the devices to be varied by downloading applications. These applications may be from sources that the user trusts, but may be from untrusted and possibly malicious sources. If a number of personal devices form a "personal area network" so are in close communication over short range links such as Bluetooth, then securing the personal area network is a difficult task as there are a number of entry point for attackers (the cellular interface of the mobile telephone, the wireless LAN interface of a PDA with a data card, the Bluetooth port on a wireless earpiece are three examples). Securing all entry points requires a competent security overseer that has authority and experience in all the communications protocols and execution environments that the devices support. Such competent security overseers are hard to realise in the personal computing space where there are multiple manufacturers and multiple or no service providers. This paper is written to to make readers aware of security threats to the successful proliferation of wearable/personal computing devices. It is written based on the author's experience with security standards and terminal specification for mobile telephones. However, as there have been telephones out for a few years now with the functionality of PDA, palmtop computers and consumer electronics devices (such as gameboys), the experience the author and his colleagues have gained in securing these sophisticated mobile telephones have general application to the area of personal and wearable computers.