var offNames = new Array("previous1", "next1");
var onNames = new Array("previous2", "next2");
var offImages = new Array();
var onImages = new Array();
for (i = 0; i < offNames.length; ++i) {
    offImages[i] = new Image();
    offImages[i].src = "../images/" + offNames[i] + ".gif";
    onImages[i] = new Image();
    onImages[i].src = "../images/" + onNames[i] + ".gif";
}    

function doOver(i) {
    document.images[i].src = onImages[i-1].src;
    return true;
}

function doOut(i) {
    document.images[i].src = offImages[i-1].src;
    return true;
}