jQuery.preloadImages = function() {
var a = (typeof arguments[0] == 'object')? arguments[0] : arguments;
for(var i = a.length -1; i > 0; i--) {
jQuery ('<img src="' + a[i] + '" height="27" width="1" />');
}
}

var preload = ['images/about_hover.gif', 'images/products_hover.gif', 'images/tech_hover.gif', 'images/news_hover.gif', 'images/customers_hover.gif', 'images/documentation_hover.gif'];
$.preloadImages(preload);
//$.preloadImages('image1.gif', 'image2.gif');