I'm not sure I can apply that here - if I'm understanding correctly I could use that technique to show the .gif additionally, but only in IE browsers; I don't see how I could use it to replace the .png altogether. The solution on your OxIce site looks so lovely and elegant, I'm tempted to steal it, but I'm so proud of my little validating-buttons (because I am, apparently, unable to resist the lure of the Gold Star).. I might try image-fiddling as a first approach.