Unless you have a security guard sitting at a monitor with his hand on a joystick scanning your property, I think that pan/tilt/zoom cameras are an unnecessary expense for a home security system. You can have a half dozen of the Airlink101 cameras mentioned by ScottC covering multiple entry points for the cost of a single pan/tilt/zoom camera.

I also like to put a camera inside the house covering an area likely to be used so that a close-up of the thieves might be obtained.

Needless to say, cameras do not prevent break-ins. A good alarm system is your first line of defense.