There is an application called Dorgem (Windows Only), which has motion detection function on normal webcam. This is a pretty cool feature because you can convert webcam to a security camera. Dorgem also has couple of other features that are useful for security camera, such as capture images and store off-site (i.e. FTP site), and supports unlimited number of simultaneous cameras.
Dorgem is a webcam capture application for Windows 9x and up. Any Video for Windows compatible webcam (or other digital camera) is supported.
It has unlimited storage events that can put the captured image on an FTP site as well as a local disk, all with their own time interval. It can put a unlimited texts and bitmaps on the captured image before the image is stored.
Dorgem supports an unlimited number of simultaneous cameras. It has a built-in webserver for still images and can be used as security camera because of its motion detection.
Simplehelp has a full tutorial on how to setup your webcam as a security camera. It should give you a head start on configuring the application.