Corporate Wide Screensaver.

I have been asked to implement a corporate wide screen saver. Something like “My Picture Slideshow” that will be updated periodically to display different messages or images. I know I can create a custom adm template and using a gpo point to a network folder containing the content. There is approx. 850 desktops on our network. I am afraid I will suck up all of our bandwidth doing this. Does anyone have a better solution?