I make a point of clearing my browser history and cache often so that doesn't happen while I'm surfing. Others may do the same so your Pre-Loading fest may go unused. It works for Netscape-style browsers, but Internet Explorer ignores it and caches away. Caching everything up front will certainly take longer than just downloading the current page images and such. You can try to get around that by only caching what will be needed for the next few pages rather than trying to throw everything down the Internet pipe at once.
Images are easiest.
We'll do them first. The example above is pre-loading three images I have named image1.gif, image2.gif, and image3.gif. The format is not new to you if you've ever tried to install almost any Image Flip JavaScript. The name of your images do not have to be image1.gif, etc., etc. You can use any names for the images.