/** Img rollover function. **/
function rollover(name,source){
    document.images[name].src=source;
}

/** Preload image function: takes an array of img srouces. **/
function preload(aImgSrc){
    for (var i=0; i<aImgSrc.length; i++){
        var newImg = new Image();
        newImg.src = aImgSrc[i];
        aImgSrc["img_"+i] = newImg;
     }
}