It is not a matter of software. Consumer-grade digital cameras are not suitable for use as webcams. This is a design issue and cannot be resolved by the consumer. Apart from the presence of a lens and image sensor, they are quite different. A webcam contains little more than a lens and an image sensor. They are designed to be controlled by a host computer, which manages most of the camera functions. Consumer digital cameras, on the other hand, are designed to be controlled by the camera user manually. They do not provide remote control functions, except in very limited way. They can be interfaced to a computer, but it usually treats them only as a removable storage device. Cameras, like the A75, that can be interfaced with a printer don't offer remote control features, either, although they do allow a degree of communication between the printer and camera to identify and move printable images from one storage device to another. This interface is limited to the functions required to select, copy, and print photographs. Many digital cameras disable their image-taking functions when connected to a computer, since these functions are not required to copy images from one device to another. It's a bit like asking someone to insert a nail with a screwdriver. They are both fasteners, but the similarities end there.

i have the same issue! i want to use my camera as a webcam...i was trying to figure how to for two hours! i have a canon too its a SD1000. if anyone knows how to connect a camera to the computer please share! T_T

Possibly though I really have no idea.