How do you stop Skype from automatically updating?

Skype

In Skype ... Tools > Options > Advanced. In the "When a new verison of Skype is available ..." section uncheck the "Automatically download and install it" check box.

If like me your camera stopped working after an update then installing version 4.0.1 (get from web) and unchecking this option will mean your camera will keep working and you won't be forced to go out and buy a webcam that Skype is getting a kickback from.