MJPEG Streamer is a sidebar gadget made in flash. It can display a mjpeg video stream in it’s native size. This gadget is optimized for 640x480 MJPEG video streams.
Because this gadget is made in flash, you will need the flash plugin for the sidebar. If you have a 64bit version of Windows (mostly Windows 7), you will need to use the 32bit version of the sidebar because there is no 64bit flash plugin yet.