Have you thought of using just one image? CSS does "preload" images if you do it the right way. After the images are loaded, it still takes time to swap the images, if you have like 30 rollover's on your page it becomes really slow. Believe me when I says CSS will never slow down your page.
Here.
http://www.simplebits.com/notebook/2...rollovers.html
If you think I want custom text, sure, easy.
Code:
#menu a { text-indent: -999em; overflow:hidden; }
So now you've hidden the text and you can use a bg image instead of normal image to show your button/navimage/whatever. The best is when the browser doesn't support styles, You can serve them text, instead of images wich might look very odd (anyone not using border="0" on images inside a hyperlink knows what I mean, stupid blue border!) , and have a clean coded navigation menu.