Preloading of images is useful to preload rollover images and to preload images for the 'next' page you're loading.
If the images you're talking about are always displayed on the current page (and espicially if that page is your entry point), there is not really any preloading involved. You may wish to optimize the graphics on the page or reduce the number of images to speed up display.
If the page is an internal page on your site, you can probably use some variation on Jeff's second suggestion.
Greg
"Personally, I am always ready to learn, although I do not always like being taught." - Winston Churchill