[ducasi]

One thing to be aware of with Skype is that (because of it's peer-to-peer nature) if you have broadband it can sometimes use your internet connection to relay other people's phone calls.

Theoretically this isn't a big problem, unless your broadband connection has strict usage caps.

I've no idea how much of a problem this is in practice for home users, but it's one reason why we've had to ban its use within our network at work...