Other users
Servicing mostly home computers it's important for us to know who else might use their computers, and how much control the client has over how they do so. Middle aged gardener using Skype to call her sister in Australia who's never heard of iTunes and wouldn't even have a credit card, let alone buy anything from a web site sounds like a pretty low risk, but her son visits on the second Sunday of each month, and he has a penchant for downloading illegal videos. And he's quite capable of switching off firewalls, AV and antispyware to do so.