I've been using yslow & firebug to detect issues with my site, and one suggestion that I know I need to do is to set expires headers for my images. I have looked high and low for how to do this, but I have not been able to find anything of real use, just that I need to. I have no problem setting the headers on css or pages, but for some reason I just can't figure out the images... it's driving me nuts! Sample code would be a miracle-- please help!

oh! I'm on an IIS server and using coldfusion for my server script.

Thanks!